362 CEETACEOUS PELECYPODA 



7. FhaseoUcama, Valenc, (Chenu, Manuel de Conch., II, 157). Shell 

 ovately elongated, equivalve, inflated, with the beaks sub-anterior, hinge tooth- 

 less ; the muscular scars are stated to be long and strong, and the pallial line 

 complete; type, PA. Magellanica, Val. The animal has the mantle with three 

 openings, the anterior being for the passage of the foot, the gills and palps are 

 elongated. Ohenu introduced this genus in the fwcnilj Mytilid^ : its form is 

 very similar to that of Modiola, but it would appear that the mantle margins are to 

 a great extent united. 



List of cretaceous species. 



Pictet and Campiclie (Mat. p. 1. Pal. Suisse, IV«^^ ser., 3^^^ part., p. SU,) admit the fol- 

 lowing species : — 



1-6. — Myoconcha SahaucUana, Loriol^ gauUinay Piet. and Gamp., cretacea, d''Orb.,. angulata, 

 d''Orb._, dilatata Zittel, and Requienmna^ Math. 



7-9. — M. elUioiica, Eomer,, minima,. Reuss, and M. (ModioUna) discrepans,. Miiller. 



M. supracretacea, d''Orb., is a problematic species, and M. Neoco mi ensis, di'Ovh.,h ^n^^o^Qd 

 to be identical with Sahmidiana. M, cretacea is given by Eichwaldalso from the so-called neocomien 

 beds at Khoroschowo and from glauconitic beds near Orenburg, and M. minima from the Cenomaoien 

 of the neighbourhood of Kiew, (Leth. ross., xme livr., 1867, pp. 538 and 540). 



10. — M, Strajewshiana, d^Orb., (ibid. p. 539,) is also placed by the same author in the neocomien. 



11. — M. Ferreti, Gueranger, Album paleon. de la Sarthe, 1867, pi. xxii, lig, 8. 



12. — M. gracilis, Brescher, Zeitsch. d. deutsch. geol. Gesellsch., vol. xv, 1863, p. 350. 



13.. — M, suh'Ovata is the only species which occurs in the South Indian cretaceous roeks. 



MYOCONCHA, Somerhy, 1825, fvide p. 360). 



1. Myoconcha sub-ovata^ StoUczka, PL XXIII, Eig. I. 



MyoG. testa suh-ovata, modice inflata, crassa, antice angitste oMusata, postice late 

 suh-rotimdata, margine dorsali leviter curvato^ ventrali sub-redo^ prope termina- 

 tionem anteriorem paulo insinuato ; umbonibus sub-anticis, depressiusculis ; superficie 

 striis incrementi lameltosis et ad marginem dorsalem duabus castuUs radiantibus 

 notata. 



Length : greatest heiglit of valves ... ... ... ... 2*02 



» * >r thickness „ ... ... ... ... 2-77 



The elongately ovate shape and rather uniform convexity of the valves 

 readily distinguish the present species from any other cretaceous form. The shell 

 is of considerable thickness, but not well preserved on the figured specimen, its 

 surface being somewhat weathered off; it shows only strong concentric stride of 

 growth. Another specimen shows near the dorsal marg^in two ribs which begin 

 at the apex and proceed posteriorly in a manner similar to that seen in M, cretacea. 

 This second specimen, being partially a cast, also exhibits the impressions of the 

 two adductors, which are of the usual form: the anterior situated on a thick 



