151 



from the Cretaceous rocks of North America, which are probably 

 nothing more than varieties of this well known European shell. 



The first of these is the Gytherea Leonensis of Conrad, which Mr. 

 Etheridge says is the commonest fossil atNanaimo * Conrad's figure of 

 C. Leonensis suggests the idea that the original may be an elongated 

 variety of Cytherea plana with a rather strongly excavated luuular 

 declivity, and an exceptionally long and nari-ow, but imperfect right 

 valve of C. plana found by Mr. Eichardson at Nanaimo rather favours 

 this hypothesis. 



Meretrix l^ippana, Conrad, of which only a single left valve is known, 

 and which is the type of Conrad's subgenus Aphrodina, is still more like 

 the present species, not only in the general outline of the shell, but also 

 in the shape of the pallial sinus and in the dentition of the hinge, as may 

 be seen by any one who will take the trouble to sompare Conrad's 

 figure of the interior of A. Tippana in the fourth volume of the "American 

 Journal of Conohology'' with the corresponding figures of the same valve 

 of C. plana in the first volume of the " Mineral Conohology," or in the 

 third of the "Paleontologia Indica." 



Caryatis nitida, Gabb. from the Chico Group of California, is probably 

 also a local variety of 0. plana. Mr. Gabb does not give a figure of an 

 adult specimen of C. nitida, but his drawing of the young shellf 

 corresponds to a not unusual form of C. plana when half grown, in 

 which the beaks are elevated and the outline of the margin of the valves 

 is somewhat rounded. 



(Cytheria Leonensis, Conrad. 



Kanaimo, V. I. Etheridge. See the remarks which follow after the 

 description of the preceding species.) 



DOSINIA GYRATA, GaBB. 

 Doiinia gyrata, Gabb.— P«l. Cal., Vol. I., p. 168, pi. 23, fig. 148. 



Sucia Islands, in Division A ; J. Richardson, 1875. A iingle right 



valve. 



Eriphyla umbonata, Gabb. 



Eriphyla umbonata, Gabb.— Pal. Cal., Vol I., p. 180, pi. 24, figs. 1«2 and 162a. 



Nanaimo Eiver, V. I., two miles and a quarter up and at the Sucia 

 Islands, in Division A ; J. Eichardson, 1872 and 1874. Five good speci- 



• Quarterly Journal of the Geological Society of London, 1861, Vol. XVII., p .432. 



tin tbe second volume of the P^'laeontology of California, pi. 30, flg. 7, which should be 

 compared with the specimen represented by stoUczka in Vol. in. of the Indian Palaeontology, 

 pL 7, flg. 3. 



