Fossils from the Hindu KhoosJi. 53 



May Hill, which is so like the Chitral specimens, even to the matrix, 

 that only close examination would enable one to separate them. 



Two or three specimens in General McMahon's collection may 

 be thus referred, 



BRACHIOPODA. 



4. Oethis striatula, Schlotheim. (PI. II, Figs. 6a, 6, la-c.) 



Orthis striatula, ScUotlieim : British Devonian Brachiopoda, p. 87, pi. xvii, 

 figs. 4-7. 



Specimens of Ortliis are rare in this collection, and owing to the 

 slipping of the valves very much thrown out of shape. Hence the 

 character of the ornamentation becomes the principal factor for 

 specific determination. The smaller of the two figured specimens 

 shows the Orthis hinge very distinctly, whilst the larger one fails 

 in this respect. Davidson's diagnosis is sufficiently comprehensive — 

 '• Shell variable, usually transversely oval or elliptical, but at times 

 the length is equal to or slightly exceeds the width." But for this 

 I might have had some hesitation in thus classifying Fig. 6, which has 

 a strong resemblance to Orthis (eqidvalvis, Dav. (Brit. Silur. Brach., 

 p. 263, pi. XXX, figs. 9, 10). As regards the ornamentation, the 

 following fairly well applies both to the larger and the smaller 

 specimen : " Exteriorly, both valves are closely covered with 

 numerous, fine, thread-like, rounded, radiating stri^, etc." 



Genus SPIEIFEE. 



There are a great many specimens of Spirifer in General 

 McMahon's collection, most of which can be focussed under some 

 of the varieties of Spirifer disj'unctus, Sowerby, as grouped by 

 Davidson. In this respect it seems to me that Davidson has made 

 his net a little too comprehensive. 



5. Spirifer extensus, Sowerby. (PI. II, Figs. 8a~d.) 



Spirifera extensa, Sowerby: Trans. Geol. Soc, ser. ii, vol. v, pi. liv, fig. 11. 

 Spirifer disjunctus, Sow., var. extensa, Sow. : Brit. Dev. Brach., p. 23, pi. v, fig. 11. 



Width of figured specimen 40 mm., length 18 mm. This gives 

 a ratio of width to length of rather more than 2 : 1. Shell alate ; 

 valves moderately convex with a deep sulcus in the ventral valve, 

 whilst the dorsal valve has the mesial fold very prominent ; hinge 

 area narrow and nearly straight. The beak of the ventral valve 

 is only slightly incurved, and but slightly projecting. There are 

 about 45 radiating costge of moderate salience on each valve, and 

 this style of ornamentation is shared by the sulcus and mesial fold. 



The Chitral fossil differs from the type-form of 8. extensus chiefly 

 in being somewhat less alate, and in having a more pronounced 

 mesial fold and sulcus. In this respect it more resembles S. calcaratus, 

 Sow., which Davidson likewise regards as a variety of the disj'unctus- 

 group. It must be noted that besides the alate character of this 

 fossil (Fig. 8) the narrow hinge area and want of salience of the 

 beak of the ventral valve serve to separate it from Spirifer 

 disjunctus (Fig. 9). 



There are two specimens in the collection. 



