1921] NATURAL SCIENCES OF PHILADELPHIA. 383 



Rissoina laevigata C. B. Ad., Tryon, Man. Conch., viii, p. 390. Dall, Tr. 



Wagner Free Inst. Sci., iii, p. 342. 

 lopsis fusiformis Gabb, Trans. Amer. Philos. Soc, xv, 1873, p. 228; Proc. A. 



N. S. Phila. 1872, p. 272. (Feb., 1873). 



The shell is smooth except for faint growth-lines, the first two 

 whorls somewhat convex, the rest fiat. The outer lip has a low 

 external thickening, and no denticles within. 



Length 3.85, diam 1.75 mm.; 8| whorls (Type). 



Length 3.35 mm. 



These notes and the figures of Gabb's type and a smaller para- 

 type are given to show the exact form he had. The type is slightly 

 larger than Adams indicates for his laevigata, the other shell about 

 the same size. They agree well with recent specimens so named. 



The type of E. crassilabris and another specimen are 

 no. 2606 A.N. S. P. 



I opsis fusiformis Gabb (Text-fig. 19) is the neanic stage 

 of this species. There are two specimens in the type lot. 

 The larger one, text fig. 19, measures 2.2 mm. long, 1.2 

 diam., having 7 whorls. The outer and basal lip is some- 

 what broken. The other specimen measures 1.65 by 0.85 



mm., with 6 whorls. The outer lip is protractive, thin, f^^- .^^- . 



11 lopsisfusi- 



and the base has a distinct if short and shallow spout, formis. 



These cotypes are no. 2621 A. N. S. P. 



Rissoina minuta (Gabb) Plate XXXIV, fig. 1. 



Cerithidea minuta Gabb Tr. Am. Philos. Soc, xv, 1873, p. 239. 



The sculpture consists of many slightly protractive and weakly 

 sinuous axial riblets, which became very weak at and below the peri- 

 phery. There are very feeble and fine spiral striae above, becoming 

 much stronger at the periphery and below it, where they are blunt, 

 cord-like, and run over the less prominent ribs. Two of the spiral 

 cords are visible on the penult whorl. There is a strong varix out- 

 side the sinuous lip. The aperture has a narrow channel above, 

 and a broad, shallow sinus below. The columellar margin is worn 

 away in the middle, as though by a hermit crab. Apical whorls 

 wanting. 



Length 4.7, diam. 2.3 mm. 



Type is no. 2818 A. N. S. P. 



This species is a little stouter than recent specimens labelled R. 

 7miUicostata (C. B. Ad.). Except for the difference in the spiral 

 sculpture, it agrees rather well with Schwartz von Mohrenstern 's 

 figure of R. midticostata (which represents R. krebsi Morch, accord- 



