6 Messrs • Newton and G. C. Crick on some 



Area, Everest .i.l'. Researches, 1833, vol. xviii. pt. 2, pi. ii. fig. 27, 



p. 114. 

 Citculla-a virgata, Blanford, Journ. Asiatic Soc. Bengal, 1863, p. 136 ; 



Blanford and Salter, Paleontology of Niti, Northern Himalaya, 



1865, p. 103 ; iion J. de 0. Sowerby, 1840. 

 Macrodon egertonianum, Stoliczka, Mem. Geol, Surv. India, I860, vol. v. 



pi. viii. lig. 7, p. 89. 

 Paralleludon egertonianus, R. B. Newton, Geological Magazine, 1896, 



pp. 294-296. 



From StoHczka's diagnosis we understand this species 

 to be an obliquely elongate shell, convex, narrow, and 

 with radiating costaj } the costa3 are fewer and consequently 

 wider apart towards the anterior margin and nearly obsolete 

 posteriorly ; concentric strige unequal, undulating, sometimes 

 lamellose. These characters are mostly well expressed in 

 the valves from Arabia now referred to this species, although 

 the posterior radiating costae are more apparent than in 

 Indian examples, a fact which is probably due to better 

 preservation. 



Rather more than eleven years ago I recognized this 

 species among the Bihin Limestone fossils of Sonialiland, and 

 I then referred to a peculiarity of ornamentation seen only on 

 the right valve, which had not previously been noticed, viz. 

 the presence of intermittent ribbing betvv^een the primary 

 radial costal, a structure wdiich I also observed at the same 

 time in some of the original Indian specimens in the British 

 Museum collected by the late Sir Richard Sirachey, and 

 which is further observable in the valves from Arabia. I 

 now find the same sculpture in J. de C. Sowerby's CucuUcea 

 virgata from the Cutch Jurassic, a species which has already 

 been mistaken for egertonionusy although it represents a shell 

 of very different contour, being more or less quadrate and, 

 moreover, furnished with almost central urabones, and alto- 

 gether lacking the obliquity of the Spiti form. 



Very similar sculpture is present on the left valve of 

 Cucullcea lasti, described by G.Muller(in Bornhardt, 'Deutsch. 

 Ost-Afrika,' 1900, vol. vii. pi. xvii. figs. 1, 2, p. 533) from 

 the Kimeridgian of German East Africa ; but that form has 

 also more central umbones, less oblique radial costas, and 

 rather more inflated valves. 



This ecjertonianus is also quite distinct from Dr. Dacqud's 

 Macrodon rufce * from the Kimeridgian of Western Somali- 

 land (Atschabo and Harro Bufa), as pointed out by that 

 author, who further regards his species ^as showing a greater 



* "Beitrage zur Geologic des Somalilandes," Beitr. Palaontologie 

 Geologie Oesterr.-Uugarus Orients, 1005, vol. xvii. pi. xv. figs. 4-6, pp. 137, 

 138. 



