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One chondrule is composed of minute lath shaped crystals of a plagioclase felspar showing multiple twinning, the laths being separated by granules of olivine.

Olivine in well shaped crystals is common (Plate 27, figs. 1 and 2). It is colourless and shows no signs of decomposition. These crystals are often separated by a cloudy mineral similar in all respects to that forming the large chondrule mentioned above.

Nickel-iron occurs in angular patches and aggregates throughout the rock. Some of this may be troilite.

One patch of colourless glass has been noticed.

The following analysis was carried out by Mr. F. R. Ennos, Analysis of the Meteo- B.A., B.Sc., A.I.C., at the Government Laboratory, London, in November 1923.

rite.

The analysis was done according to the method described in the Mineralogical Magazine, Vol. XIX, No. 98, pp. 323-329, September 1922.

About 23 grammes of the meteorite were crushed and separated by a weak magnet into attracted and unattracted portions, weighing 5-7970 grammes and 17-2274 grammes, respectively. Each of these portions was analysed separately. The bulk composition was calculated from the relative weights and analyses of the attracted and unattracted portions.

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99.89

100-18

100-08

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The above results indicate that the Merua meteorite belongs naturally to group 2, Cronstad Type of Dr. Prior's classification.1

1 G. T. Prior, Min. Mag., 1916, Vol. 18, p. 30. 1920, Vol. 19 p. 61.

STEGODON GANESA (FALC. AND CAUT.) IN THE OUTER SIWALIKS OF JAMMU. (With Plate 28). BY D. N. WADIA, M.A., B.SC., Geological Survey of India.

THE

HE fossil remains which are described in the following paper consist of a tusk (left upper incisor), of the extraordinary length of over 10 ft., together with the maxillary part of the cranium with which it was in organic connection. They were found by the writer in 1922, near the village of Jagti (long. 74° 57', lat. 32° 47′) six miles due north of Jammu, and are preserved in the Geological Museum of the Prince of Wales College, Jammu.

The fossil occurred in a series of clay beds interstratified with soft incoherent grey sand-rock-a lithological assemblage typical alike of the lower part of the Upper Siwalik stage as well as the topmost part of the Md. Siwalik of the foot-hills zone of Jammu. The tusk was implanted in its deep alveolar cavity in the cranium. The stump of the second right, upper incisor, about a foot in length, was also in situ in the upper jaw. The maxilla bore two large massive molars separated by a strongly concave narrow palatine. No trace was found of any of the mandibular rami although a close search was made for them, nor of any of the lower molars.

The skull unfortunately crumbled when dug out, but from the discolouration produced in the mould of the cranium, it was possible to make out the main outlines of the skull and the great temporal fosse characteristic of this species of Stegodon.1

The cranium.

The only bones of the skull which were to some extent preserved were the maxillæ, the palatine, a few plates of the nasal and frontoparietal regions, and parts of the occipitals with the two condyles. The palate is a flat plate of bone, broad behind and narrowing anteriorly. Measurements of the width of the plate are as follows:

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1 Fauna Antiqua Sivalensis London, 1846.

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Teeth.

The greatest vertical diameter of the occipital condyle is 4.6 inches; its transverse diameter is 3.7 inches. The teeth that are seen in the present fossil are the last, or the 3rd true molars and are well implanted in the palate in deep alveolar cavities. There is no indication of the preceding second molar nor of any of the so-called "intermediate" molars.

The molar is about 10

inches long, with a maximum width of 4 inches in the middle, the crown being 3-5 inches high above the alveolar rims. The front parts of both the molars are damaged, one, or possibly two,

Molars.

of the most anterior ridges being missing. But from the extension of the socket-cavity and the examination of the embryo-tubercles of dentine, it appears that the total number of ridges could not have been more than ten. In addition there are two aft talons or incipient ridges with 3 small cusps sprouting at the posterior end. The enamel on the dentine is still perfect; the cement is plentiful and fills both the cavities inside the ridges as well as the intervening valleys between them. The number of cusps on any of the ridges does not appear to be greater than 6 or 7, a number which falls considerably short of the specimens of the same species described by Dr. Falconer and Mr. Lydekker; the most posterior talon has 3, the one following that 3 or 4, which in turn is succeeded by a ridge carrying 5 well-defined cusps. The more anterior ridges, formed by the complete fusion of the cusps, are curved, and are more irregular and wider than the posterior ones. All the ridges are well-defined and fairly elevated, though well worn and blunt at the apex. They rest on broad bases with shallow intervening valleys deeply filled with cement. The long axis of the 6th, 7th and 8th ridges is between 3-8 and 4.2 inches and the greatest average width about 0.75 inch. The depth of the valley between the 6th and 7th ridges is 0.37 inch; the intervals between the summits, of the consecutive ridges is about 0-4 inch. There is no mesial cleft or line traversing the crown, a fact which distinguishes the less specialised mastodons from stegodons. The crown of the tooth is flat by wear, and is almost rectangular in front, this and the solitary last molar point to an individual of some age. The plane of wear of the tooth slopes antero-posteriorly and not as in Stegodon clifti from the outer to the inner side,

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Incisor.

The incisor or tusk, the principal part of the present find, though cut up by a number of transverse cracks, is the best preserved part of the fossil. At the thicker proximal end the tooth is ensheathed in a thick bony covering the incisive sheath, portions of which adhere at some places. The external as well as the internal characters of the tooth are accurately preserved, including the structure of the dentine. In its microscopic structure it scarcely differs from ordinary "living" or green ivory, being composed wholly of densely packed bundles. of fine fibres, intersecting each other in long circular arcs. The peculiar "engine turned" marks thus produced, which are so characteristic of true ivory, are clearly seen on all transverse sections. The petrification of the distal 3rd part of the tusk is somewhat better than the proximal 3rd.

The following measurements give the necessary dimensions of the tooth

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The length, width and the ridge-formula of the upper molars of the present fossil agrees with the species S. insignis, Falconer and Cautley,1 which is distinguished from the Systematic position. other species of the sub-genus by a higher ridge-formula, greater dimensions of length and width and by the plane of wear of the molars being from the anterior to the posterior extremity, as well as by the greater amount of cement filling the intervals between the ridges. Dr. Falconer, however, founded a new species of Siwalik Stegodons-S. ganesa which he believed to have arisen from S. insignis by a greater differentiation in certain cranial regions and by development of larger incisors-characters which many now regard as indicating nothing more than sex distinctions. According to these observers S. ganesa is merely the male of S. insignis. The markedly large size of the present tusk is an

Fauna Antiqua Sivalensis, London, 1846.

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