IC6 



the lašt whorl, and narrowest part of it close to the aperture, or the 

 penult whorl. 



With, then, the oue species frora Polynesia, Electrina succinea, 

 the totai of Stoastomidce amount to 8 1 species known ; and I proceed 

 to propose aii entirely new arrangement of them. Professor Adams 

 foresaw the necessity and propriety of it. In his ' Monograph of 

 Stoastoma,' p. 4, oecur the foUovving passages : — "The value of this 

 genus is equal to that of the Lamarckian genera of Cyciostoma and 

 Helicina. If these should he generally received as families, sub- 

 divided into several genera according to the plan of Dr. L. Pfeiffer, it 

 will be entitled to constitute a distinct family, Stoastomid^e. Some 

 of the characters rarely, if ever, oecur in other genera, while the 

 specific differences consist partly in slight modifications of these 

 characters. Such are the blunt but not reflected edge of the labrum 

 and the spirai lamella issuing from the umbilicus. The genus has 

 thus a very obvdous type, quite distinct from any hitherto discovered. 

 An affinity with the CyclostomidcB is established between Apero- 

 stoma (Troschel) and the depressed and discoidal species of Stoa- 

 stoma." " Its affinity with the Helicinidce is estabhshed betweeu 

 Lueidella (Swainson) (? ?), and some of the conical species, as S. 

 Redjieldianum and S. Leanum, by their general form and sculpture, 

 and by the form of the base. But observations on the animals will 

 be of more value on this subject. We were not so fortunate as to 

 obtain living specimens. While preparing this Monograph, a cor- 

 respondent informs us that S. pisum when alive is sea-green." 



In raising Stoastoma into a family, I am thus justified by Pro- 

 fessor Adams, and only carry out his views in calliug it, Family 

 Stoastomidce, x\.dams. 



Fortunately I happen to be " the correspondent " who found the 

 shell S. pismn in " a living statė ;" when it is, and continues after, 

 if so taken, of a "sea-green" colour externally. I have also exa- 

 mined the outward form of the animal. The followiug are my rough 

 original notes made long ago upon it : — 



"Stoastoma pisum. 

 "The animal seems to have but one pair of horns, and is thus 

 -shaped. 



[The drawing snpposcs the animal to be in motioii.] 



