CYPRINA. 145 



numerous W-sliaped markint>-s on the surface. Tliese appear to l)e clue to the 

 structure of tlie shell (possibly connected with colour markings), since they are 

 seen only in specimens which are somewhat decorticated, and are in some cases 

 present on one valve but not on the other, or are seen on the dorsal but not on 

 the ventral part of a valve. 



Stoliczka' thought that Venns Hnnolnta was probably identical with Cijthpren. 

 jilana, Sowerby, but the hinge and pallial line of the former prove conclusively 

 that it belongs to the genus Gi/priua. 



Types. — From Blackdown ; Venus Uneolata in the British Museum ; (,'. rosfrtiln 

 in the Bristol Museum. 



Distrihnfloii. — Upper Greensand (zone of Schloenbochia rostrata) of Blackdown. 



CvrruxA (Vi-^nilicardia) tkuncata (Suwry/ji/), 1836. Plate XXIII, fig. 3. 



183G. Venus ? truncata, /. dr C. Sowcrhy. Trans. Geol. Soc, scr. 2, vol. iv, 



pp. 242, 341, pi. xvii. fig. 3. 

 1850. — suBTRUNCATA, A. irOrbiijiitj. Prodr. de Pal., vol. ii, p. 159. 



18.54. CvTnEREA TRUNCATA, /. Morris. Cat. Brit. Foss., ed. 2, p. 201. 

 1865. Venus subtruncata, F. J. Piciet and G. Campiche. Foss. Terr. Cret. Stc. 



Croix (Mater. Pal. Suisse, ser. 4), p. 190. 

 1870 — — ii". Stoliczka. Pateont. Indica, Cret. Fauna S. India, 



vol. iii, p. 161 (Caryatis). 



Affinities. ^=^—0. truncata is closely allied to, and probably only a variety of 

 C. angidafa. The shell is thinner, the posterior margin higher, and the anterior 

 part more produced than in C. anguluta. 



This species, or variety, has hitherto been referred to Yenva or Cijtiieren, but 

 a specimen showing the hinge and pallial line proves that it is a Ci/priiia. The 

 hinge agrees with that of (J. angulatn. 



An example collected by the late Rev. W. Downes (Plate XXTII, fig. 4) is 

 more elongated and more inflated than the type of G. truncata, but agrees in other 

 respects, and is probai)ly only an individual variation. 



jTy/jJC. — From Blackdown ; in the Bristol Mu.seum. 



Distribution. — Upper Greensand (zone of Schla'tibachia rostrata) of Blackdown. 



CvnaxA i,I(;ei!IKXSis, crOrbignij, 1844. 



Tntornal casts of a large Ci/prina have been found in the C'enomanian 

 Siiiidstdnc (if Wilmington,- Devon, and in the cherty blocks in the Eocene Cnivel 



' • Cret. Fauna S. India,' vol. iii (1870), i)p. 1(J0, 1G9. 



- Jukes-Browne, 'Cret. Bocks of Britain,' vol. ii (1903). p. 129. 



