rOSSlL ECHINOIDEA 01" LAKE UEMI. 



Dimensions. 



421 



Affinities. — A large specimen of this species was figured by 

 Abich as Olypeaster turritus, Philippi, a species which was 

 admirably figured and described by its founder *. The specimen 

 referred to 0. turritus by Abich. seems to me a very distinct form. 

 In G. turritus the height is almost exactly half the length, 

 whereas in Mr. Giinther's specimen it is less than a third the 

 length ; in Abich's specimen it is almost a third the length. A 

 still more important difference is ia the length of the petals. 

 In C. turritus the ratio of the length of the petal to the 

 non-petaloid portion of the ambulacrum between the petal 

 and the ambitus is as 2 : 1. In C. Q-uentheri the ratio is 

 as 3 : 1. 



C. turritus is one of the conical, pyramidal species of Clype- 

 aster. O. Guentheri, on the contrary, is one of the flat-topped, 

 depressed species. Its nearest ally is C. gihhosus (Risso) ]", which 

 differs in having a higher and longer test and fewer granules on 

 the interporiferous ridges. 



Eischer % has already suggested that Abich's G. turritus should 

 be included as a synonym of G. gihhosus. But Pischer figured 

 as G. gihhosus an echinid which is distinct from Abich's G. gih- 

 hosus ; Pischer's G. altus § is, however, probably the same as 

 G. Guentheri and G. turritus of Abich. 



* E. A. Philippi, " Ueber Clypeaster alius, C. turritus, und C. scillce," 

 PalfEontogr. vol. i. 18—, p. 323, pi. xxxviii. figs. 1-5. 



t (ScMzJefe ^iMosa, Eisso, Hist. Nat. Europe merid. 1826, v. p. 284; Michelin, 

 op. cit. p. 120, pi. sxii. figs, a-g, pi. xxiii. figs. 1, a-c 



X p. Fischer in Tchihatcheff, "Asia Mineure," Paleontologie, 1866-69, p. 306. 



§ Ibid. p. 308, pi. vii. fig. 1. 



