380 THE CANADIAN NATURALIST. [Dec. 



would by otlier carcinologists be thought worthy of disthict specific 

 rank ; but, considering the small number of specimens at my 

 disposal for examination, I have thought it better to err, if err I 

 must, by allowing too much latitude to variation, rather than by 

 unnecessary species-splitting. The variation, though in most 

 cases such as to be almost incommunicable by drawings or written 

 description, is nevertheless sufficient to be puzzling, consisting in 

 very slidit modifications of the shell in almost all directions — in 

 outline, proportions, and degree of surflice-ornament. Such re- 

 marks as I have thought it necessary to make on these points will 

 be found under the names of the different species. 



It would be unwise to generalize hastily from the small number 

 of dredgings here described ; yet we cannot help noticing that the 

 general facies of this fauna much more nearly approaches to that 

 of the Shetland seas or of the Scottish glacial clays than it does 

 to that of England, while it has scarcely any thing in common 

 with that of the Mediterranean. The species which give it an 

 emphatically boreal character are Cijtliere leioderma (perliaps the 

 most abundant species in these dredgings, and hitherto found only 

 in the Shetland seas), C. emarginata , C. cosfafa and Cytlieridca 

 Sorhyana^ all of which may be said to range, on our side of the 

 Atlantic, north of the 60th degree of north latitude. And several 

 other members of the list become with us very scarce south of 

 54-° : these are Cytliere concinna, C. Jutea, C. tuherculata, C. 

 duncimensis. Cj/theridea pajyiUosa, and C. punctillata. Except 

 the three species here described as new, these two lists include 

 all the characteristic species of Dr. Dawson's dredgings, the rest 

 being represented in each case only by one or two specimens, 

 often imperfect. 



Argilloecia, sp. 



One specimen, possibly referable to A. ci/Ihidrica, Sars. 



Cy there leioderma, Norman. 



(Norman, Shetland Dredging Report, p. 291.) 



Carapace, as seen from the side, subquadrate, slightly higher in 

 front than behind; greatest height situated at the anterior 

 third, and equal to about half the length ; anterior extremity 

 obtuse, obliquely rounded ; posterior subtruncate, sinuated in 

 the middle : superior margin scarcely arched, obsoletely angular 

 about the eye-tubercles ; inferior nearly straight, with a slight 



