1(10 



described Eui-ojiean species. On a cursory examination the markings of 

 its valves remind one, in a general way, of those of Plicatula, or of some 

 species of Alectryonia. The folds diverge downwards and outwards to the 

 lateral margins on either side, the points of divergence being coincident 

 with an oblique line which might be drawn from the posterior side of 

 the beaks to the centre of the opposite extremity. In some specimens 

 the folds, whose summits are invariably rounded, are prominent and 

 distant; in others they are not so much elevated, and closer together. 

 The largest individual collected by Mr. Eichardson is fully live inches 

 and a half in height, from the summit of the beaks to the opposite 

 margin. 



Inocebamus mytilopsis, Conrad. 



Plate 20, figure 3. 



Iiioceramus mi/tiloides, Rcemer. — Die Kieidebildungen von Texas, p. 60, pi. 7, fig. 5 



(As of Mantell.) 

 Inoceramua viytilopsis^ Conrad. — Emory's Rep. U. S. and Mex. Bound. Surv., Vol I., p. 



152, pi. 5, figs. 6ff, b. 



Texas: Rcemer and Conrad. Septarian clays at Nanaimo and Yaldez 

 Inlet; Etheridge. Trent River, Y. I., above and below the fiills, also 

 Bradlej' Ci-eek, in Division B ; J. Richardson, 1871. 



As will be seen b}' the synonjmiy above quoted. Dr. Ferdinand Roemer 

 has identified this shell with the Inoceramus mytiloides of Mantell, which 

 most paheontologists have united to the widely distributed I.problematicus 

 of Schlotheim, Avhile Conrad regards it as a distinct species. The Trent 

 River specimens of 7. mytilopsis are in all respects similar to the Texan 

 shell figured by Roemer, and both differ from the typical form of f. myti- 

 loides or /. problematicus in their proportionately longer hinge line, which 

 runs much more nearlj' parallel with the longest axis of the valves, also 

 in their more closely arranged and more regular concentric folds, which 

 might justly be described as ribs. The anterior border of most indivi- 

 duals is truncated inwardly and oblitj^uel}^ beneath the beaks, and the 

 posterior portion of the pallial border is nearly straight, so that the 

 margin of the lower half of the shell is subangular in the middle; the 

 posterior extremity also is subtruncated. These latter characters, how- 

 ever, are no'' constant, for in one or two of the Yancouver examj^les of 

 I. mytilopsis the margin of the lower half of the shell is not subangulf r 

 in the middle, but forms a broadly rounded semiovate curve which 

 extends from the beaks to the termination of the pDsterior end below, 

 and the hinder extremity is narrowly rounded. 



