102 CARDIAD.E. 



meter, with the animals of the C. nodosum, that they are 

 identical. 



If it had been our practice to generalize,, the singular same- 

 ness of the organs of this genus would have authorized a 

 departure from the plan of detailing the specialties of every 

 case : the present work is not intended to be subjected to the 

 dull and heavy labour of being doggedly read through con- 

 secutively; we consider it one of particular reference, and 

 think that Ave have done good service to the reader in stating 

 the specialties at length in nearly every case. 



C. NORVEGICUM, Spengler. 



C. norvegicum, Brit. Moll. ii. p. 35, pi. 31. f. 1, 2; (animal) pi. N. f. 1. 

 C. Iceviyatum, Auctorum. 



Animal thick, suboval, elongated, the vertical measure 

 exceeding the transverse; the mantle is closed throughout 

 the posterior range, and at its lower part forms two short 

 siphons united at their bases and divergent at the extremities, 

 of a pale yellow, marked with flake-white spots and lines ; the 

 branchial tube is rather the shorter, but of greater diameter, 

 and is rarely extended more than half an inch; its orifice is 

 circled with twenty long yellowish-wliite cirrhi, having dull 

 red-broAvn markings around their bases; the anal siphon is 

 simple, and has the usual retractile valve, which is marked on 

 the lower and upper surface with a faint red-brown line, and 

 points of the same colour at the termination. The siphons 

 and the posterior range are clothed with thick-set pale reddish- 

 brown and pale yellow curved filaments. The mantle, from 

 the point where the filaments terminate, is simple and open, 

 with its outer and inner margin of a flesh colour, and affords 

 a passage to a long, powerful, geniculated, cylindrical foot, 

 that has a pointed termination ; its substance is rigid, and, 

 except the white point, of a red flesh colour, which the slightest 

 touch removes and shows the white ground ; it is longer than 

 the greatest measure of the shell, and its epidermis appears 

 shagreened and marked with anastomosing fine lines. There 

 are on each side a pair of pale brown suboval branchiae, with 

 the margins of a deeper bro\vn ; the upper one is considerably 



