286 BULLETIN OF THE 



striate, opening below the anterior adductor, without palpi ; foot cylindrical, 

 large for the size of the animal, distinctly grooved behind ; laterally somewhat 

 compressed near the acute tip ; base set as it were in a socket, which, when cut 

 open, shows a chamber of considerable size well suited for a marsupium ; in 

 this specimen the aperture of this chamber fitted closely around the foot, which 

 stood like a stopper in a bottle ; on each side of the foot and attached to the 

 margin of this opening was a single lanceolate, small stout fleshy gill laterally 

 longitudinally sulcate, and very small for the size of the animal ; * the posterior 

 side of the foot was distinctly grooved, but no byssus was present. 



It will be noted that these features agree essentially with the soft parts of 

 Lyonsiella abyssicola as described by Sars, and vindicate the judgment of 

 Jeffreys, who approximated the two groups. 



The type of Verticordia as restricted is V. cardiiformis Sowerby (Min. Conch., 

 pi. 639, 1844). 



To this group I refer V. acuticostata Philippi ; V. Deshayesiana Fischer 

 {-\-Japonica A. Ad.) ; V. Woodii Smith; V. tomata Jefi'reys; V. flexuosa and 

 V. granifera Verrill, the former described as a Mytilimeria by that naturalist; 

 V. parisiensis Deshayes; V. perversa and V. Seguenzce, n. s. 



The type of this group resembles Trigonulina in its narrow form and exter- 

 nal sculpture, but not in hinge characters. 



Trigonulina (D'Orbigny, 1845, + Trigoniluna Chenu, 1662, -f Hippagus 

 (sp.) Adams and Reeve, not Lea). 



Shell compressed laterally; ossicle long, narrow, rectangular, flat; right 

 valve as in Verticordia, but with a long lateral tooth; left valve as in Verti- 

 cordia. Type T. ornata D'Orbigny. Cuba. 



To this group belong V. novemcostatus Ad. & Rve., and V. coelata Verrill; 

 all of which appear to be specifically identical with the type, which is found 

 in Japan, California, the West Indies, and on the eastern coast of the United 

 States. I have not been able to find the ossicle in all the specimens of this 

 species examined, even when the dry remains of the animal were in the shell. 

 But this may be accounted for by its form and extreme narrowness, which, 

 added to its position on a ligament which must be broken to open the shell, 

 render its loss extremely probable except under peculiarly favorable circum- 

 stances. 



(?) EuciROA (Dall, 1878, Bull. M. C. Z., IX., 1881). Shell large, thick, 

 Cvthereae-form, with a true lunule and corselet; ossicle triangular, wider 

 behind; soft parts unknown. Type V. elegantissima Dall. 



This species is separated chiefly by its form, the hinge being essentially like 

 that of Trigonulina, except as regards the ossicle, which from the arrangement 

 of the ligamentary scars must have been of a wide subtriangular shape. The 



* These are probably what A. Adams took for palpi in his description of the 

 soft parts of V. Japonica or Deshayesiana. 



