392 PULMONIFERA. 



slightly crenulated by the revolving lines ; inner lip arched with 

 three inconspicuous, oblique folds, of which the middle one is 

 largest ; a thin coating of enamel spreads upon the anterior whorl 

 in mature specimens ; base sub-channelled. Length, eleven twenti- 

 eths of an inch ; breadth, seven twentieths of an inch ; divergence, 

 fifty-eight degrees. 



Found in fishes taken in various parts of Massachusetts Bay, and 

 usually occupied by a hermit crab. It is somewhat abundant. Cape 

 Hope, James's Bay, 32° 10', dead (^Drexler) ; Eastport {Cooper^ ; 



Banks (mV/w). 



It was iirst described by Mr. Couthouy* under the name of C. 

 buccinoides, a name previously given to a species from the Pacific 

 by Mr. Sowerby ; on which account Dr. Jay has since applied to it 

 the name of its first describer, — a merited compliment, but in con- 

 formity to what seems to me a very bad custom. It is not at first 

 o!)vi()us to what genus this shell belongs; Mr. Sowerby coincides in 

 the opinion that it is correctly referred to CanceUaria. He states, 

 moreover, that he has for several years possessed it, brought from 

 the Arctic seas. Hence, it is probably more abundant to the north 

 of us. It varies considerably in its external appearance, from the 

 greater or less ])rominence of the folds and stritie. A specimen be- 

 longing to I)r. Prescott, of Lynn, measures seven tenths of an inch 

 in length, and four tenths of an inch in breadth. It somewhat re- 

 sembles C. cmstmlis, Sowerby. This is the only species of the genus 

 found in the Northern Atlantic, so far as I am aware. 



Sub-Class PULMONIFERA.t 



Breathing organ in the form of an air-sac or dorsal cavity, lined 

 by a vascular network. Heart situated before the lung ; abdomen 

 rudimentary, or spiral and well-developed, usually protected l)y a 

 shell. Sexes separate, or united in the same individual. Adult 

 and larva shell-bearing ; larva shaped like the parent, not furnished 

 with cephalic fins. 



Terrestrial or aquatic, respiring free air. 



* It is now considered synonymous with Tritanium rlridulum of Fahricins. — W. G. B. 



t Dr. Gould had prepared nothing on this sub-chiss. 1 have introduced descrijitions of 

 additional species and .added to the descriptions of the species included in the former edi- 

 tion by copyin-,^ from the "Land and Fresh-water Shells of North America," Part I. and 

 Part II., prepared for the Smithsonian Institution. Professor Henry has authorized the 

 use of woodcuts intended for those works, and Mr. E. S. Morse has furnished many used 

 by him in the " American Naturalist." — W. G. B. 



