295 



forward, placed in advance of the midlength : cardinal area very large, 

 broad and marked with well defined, divergent, ligamentary grooves : 

 posterior area not distinctly defined, indicated only by an abrupt inflec- 

 tion of the valves. 



The foregoing description is based almost exclusively upon the large 

 and presumably adult specimen figured on Plate 38, which was collected 

 at the east end of Maud Island, by Dr. Newcombe, in 1895. The surface 

 of this specimen is not very well preserved, and its markings consist only 

 of closely disposed concentric strife. In the small, crushed and imperfect, 

 but testiferous specimen from the same locality, described on page 235, of 

 the third part of this volume, the surface markings are well preserved 

 and consist of numerous and densely crowded minute concentric raised 

 lines, with a few rather coarser incremental ones, both of which are 

 crossed by almost equally minute radiating ridges. On the posterior 

 portion of each valve of this specimen the radiating ridges are close to- 

 gether and not very prominent, but on the central and anterior portions 

 they are distant and rather larger. 



The dimensions of the specimen figured are as follows : maximum 

 length, 117 mm. (or upwards of four inches and a half) : height, inclusive 

 of either umbo, 86 mm.; greatest breadth or thickness through the closed 

 valves, 100 mm. (or almost four inches); approximate distance between 

 the two beaks, 33 mm.; maximum thickness of test, 5^ mm. 



" Skidegate Channel west of Alliford Bay " (and probably Maud 

 Island) J. Richardson, 1872 : the two large casts indicated on jDage 73 of 

 the first part of this volume. East end of Maud Island, G. M. Dawson, 

 1878, the small crushed specimen already referred to; and C. F. New- 

 combe, 1895, che large and testiferous specimen figured on Plate 38, 

 and a distorted cast of the interior of another. 



The specimens collected by Drs. Dawson and Newcombe show that the 

 shape of the shell is not so different from that of the Cucullcea from the 

 Nanaimo group of Vancouver and the Sucia Islands, that has been 

 referred by the witer to C. trun'iata, Gabb, as was supposed when only 

 the two casts collected by Mr. Richardson were available for comparison. 

 But there are now some reasons for thinking that the specimens from the 

 localities last mentioned may be specifically, or at any rate varietally 

 distinct from the true C. trnncata. Through the kindness of Prof. Pilsbry, 

 the writer has recently been able to examine and study ten authentic 

 examples of that species, from Cottonwood Creek, the property of the 

 Academy of Natural Sciences of Philadelphia. The largest of these 

 specimens, however, is only forty-nine millimetres in length, by thirty-six 

 mm. in height, inclusive of the umbones. They seem to differ from the 

 Maud Island specimens, and from those from Vancouver and the Sucia 



