VOL. XVII. (2) JURASSIC GERVILLI^ 247 



from the Capricornus-Beds were also measured, and the results 

 showed the mean values of the ratios height /length and hmge- 

 line /length to be -64 and 1-03, respectively. The hmge is thus 

 relatively longer than in mature forms of Gervtlha Icevts, but 

 from observations on the halt-hnes of the latter, it appears 

 to be about the same as it would be in specimens of G. lavts 

 of corresponding size. None of the small forms has been known 

 to exceed 13-5 mm. in length. 



Gervillia betacalcis Quenstedt (Der Jura, 1856, tab. 12, 

 fig. 19) resembles this species, but appears to be a shorter and 

 more rounded form. Quenstedt's figure depicts a damaged 

 specimen which does not show the shght byssal sinus which 

 is always present in mature forms of G. Icevis. 



Records.— Stfiatum-Beds, Battledown Brickworks, Cheltenham (common ; 

 tvpe-locality) : Striatum- or Capricornus-Beds (probably latter) Prestbury 

 (wen at Queen's-Wood Cottages), near Cheltenham . Pilford Cheltenham 

 Ind in thi Railway-cutting (G.W.R.), Greet, near Winchcombe^ J^M.^nl^ 

 forms occur in abundance in beds of capricornus hemera at Aston-Magna 

 Brickworks, near Moreton-in-the-Marsh : Robins' Wood Hill, near Gloucester, 

 and at Dumbleton Brickyard, near Beckford. 



GERVILLIA LATA J. Phillips. PI. xxviii., figs. 4a, b and c. 



T.d. 1829. Geology of Yorkshire, pt. I., p. 156. 



T.f. Ibid., pi. XL, figs. 16 and 17. 



T.l. " Blue Wick [Ravenscar, Yorkshire]." 



H. " I[nferior] 0[olite. Dogger] " [Aalenian] 



Yf. [murchisonce] 



Colin. York Museum. 



1835. Phillips, Geol. Yorksh., pt. I., (2nd ed.), p. 128., pi. xi., 



figs. 16, 17. 

 1875. Phillips, ibid, 3rd ed., p. 247, pi. XL, figs. 16 and 17. 



Remarks.— In the third edition of Phillips' work, two 

 views of this fossil are given : one a general view of the speci- 

 men ; the other of the hinge-area— but magnified, and showing 

 the ligamentary pits. The specimen in the York Museum, 

 however, does not exhibit these pits and therefore, presumably, 

 the specimen is not the holotype, but a syntype. It is desirable 

 to make it the lectotype. It came from the red Dogger of 

 Blea Wyke, below Ravenscar, and has the following measure- 

 ments : length (parallel to the hinge-line), 47 mm. ; height, 

 32 mm. ; diameter, 19 mm. ; length from anterior to posterior 

 extremity, 51 mm. The left valve is more convex than the 

 right and overlaps along the ventral margin. 



