296 



Islands that have been referred to C. truncata, in their uniformly smaller 

 size and more particularly in their proportionately narrower and more 

 pointed umbones. It is just possible that the Maud Island specimens 

 may prove to be nothing more than a large, ventricose, thick-shelled, local 

 or stratigraphical variety of C. truncata, with a very broad, ligamentary 

 area, but for the present it is thought desirable to distinguish them by a 

 different specific name. 



MODIOLA PERSISTENS. (N. Sp.) 



Plate 37, figure 5. 



Modiola, (Sp. Undt.) Whiteaves. 1876. This volume, part 1, p. 73. 

 Modiola subimbricata, Whiteaves. 1884. Ibid., pt. 3, p. 237. But probably not M. 

 subimbricata. Meek, 1873, which is said to be a Jurassic species. 



Shell of medium size, moderately elongated and slightly arched, rather 

 strongly convex, usually higher than broad, but in one adult specimen 

 broader than high, most prominent in each valve on the umbonal declivity 

 (in the direction of a line that might be drawn obliquely backward and 

 downward from the beak to the base) below and in front of which there 

 is a shallow depression and above it a convex inflection of the valves. 



Anterior side short : anterior end rounded and narrov/ing rapidly into 

 the base, below the beak : posterior side much longer than the anterior 

 and somewhat expanded vertically, highest or deepest at about the mid- 

 length : posterior end obliquely subtruncate above, rounded and slightly 

 produced below .• ventral margin shallowly concave in some specimens 

 but nearly straight in others : superior border gently and slightly arched, 

 ascending gradually from the anterior end to about the midlength and 

 then sloping gently downward : umbones depi'essed, beaks curved inward 

 and forward, anterior and terminal. 



Surface marked by numerous, minute and close-set, concenti'ic strife, 

 also hy coarser and more distant incremental lines 



East end of Maud Island, C. F. Newcombe, 1895 : two well preserved 

 but not quite perfect specimens ; besides those referred to in the first and 

 third parts of this volume, as having been collected by Mr. Richardson 

 and Dr. Dawson. 



Melina Skidegatensis. 



Melina mytiloides ? Lamarck. Whiteaves. 1876. This volume, pt. 1, pp. 80—82, figs. 



8, a-d. 

 Melina Skideijateims, Whiteaves. 1884. Ibid., pt. 3, p. 239. 



East end of Maud Island, C. F. Newcombe, 1895 : an imperfect but 

 characteristic specimen. North side of Maud Island, C. F. Newcombe, 

 1897 : one specimen. 



