VOL. xvii. (2) JURASSIC GERVILLLE 243 



The syntypes, of which there are two, are in Jermyn Street 

 Museum (Nos. 3684 and 25177). They are from the " Lias, 

 Railway cutting . . . between Gloucester and Bredon." 

 No. 3684 is the specimen figured by Buckman and may be 

 taken as the lectotype. 



Owing to the indefiniteness of the locality given, it is 

 impossible, to determine the exact horizon of the beds from 

 which these specimens were obtained. It may be stated, how- 

 ever, that probably the highest beds exposed during the con- 

 struction of the railway (Midland) between Gloucester and 

 Bredon were armatum-heds, and it is improbable that there 

 were any seen of earlier date than turneri. Moreover, James 

 Buckman on page 84 {loc. cit. supra) definitely gives Bredon 

 as one of the localities at which this species was found, and it 

 is known that the cutting at Bredon Station is in beds of about 

 ohtusi-stellaris hemerae. 



Records. — Apart from the type-specimens only one other record of this 

 species has come under my notice, namely that of a left valve from the beds 

 of oxynoti-armati hemerae at Gloucester Gas-works. 



GERVILLIA CRASSICOSTA Morris and Lycett. 



T.d. 1853. Monogr. MoUusca Gt. Oolite, pt. II., p. 23. Pal. Soc. 



T.f. Ibid., tab. II., fig. 9. 



T.l. "Minchinhampton Common, [near Stroud, Gloucestershire]." 



H. "Great Oolite." [Bathonian] 



^. [" maxillatce "] 



Colin. Mus. Pract. GeoL, Jermyn Street, London. [9177] 



Type-description. — " Test valde obliqud elongatn , convexiuscula , auriculo 

 antico rotundato, postico truncato et brevi ; costis radiantibiis subundatis, 

 elatis majoribus 8, alternatim minoribus, et cum striis ivansversis numerosis , 

 indentatis, latere postico elongato : valvd dextrd ignotci. 



" Shell very oblique, elongated, convex, anterior auricle rounded, pos- 

 terior auricle short and emarginated ; radiating costae slightly waved, ele- 

 vated, the larger, 8 in number, distant, and alternating with as many smaller, 

 and impressed with numerous rather indistinct transverse striae : posterior 

 and inferior extremity elongated and slightly acuminated ; right valve 

 unknown. 



" Of this rare species we have only obtained three examples ; the hinge 

 border is much shorter than in Pteroperna costatitla, the posterior wing being 

 but little produced ; the whole contour of the shell is very oblique and the 

 larger costae are very prominent ; the greater degree of obliquity, convexity 

 and alternation of the costae readily serve to distinguish it from P. costatula." 



Record. — The holotype is the only specimen I have seen. 



