Hee NAUTILUS. 
Vol. XXXIV JANUARY, 1921. No. 3 
ANCYLUS OBSCURUS HALDEMAN AND SPECIES REFERRED TO IT. 
BY BRYANT WALKER. 
( Continued. ) 
Through the courtesy of M. Menard of the Museum of 
Geneva, Switzerland, I have received photographs and other 
valuable data in regard to the types of the unfigured West-In- 
dian species of Ancylus described dy Bourguignat and have con- 
sequently been enabled to differentiate the following species 
with more certainty that I otherwise should have been. 
IV. 
Ferrissia jamaicensis n. sp. Pl. III, figs. 1-3. 
Shell depressed, oval, slightly wider at the anterior end; 
lateral margins equally curved; anterior slope nearly straight, 
being very slightly convex towards the apex; posterior slope 
concave; the left lateral slope a little convex; the right lateral 
slope concave; apex obtuse, excentric, turned toward the right 
side, obscurely radiately striate, situated about halfway between 
the median line and the right margin and at about two-fifths 
of the length from the posterior end; lines of growth fine, but 
distinct and regular, with traces of subobsolete wrinkles on the 
anterior slope; light horn color. 
Length (type) 5.25: width 3.5, alt. 1.5 mm. 
Length (paratype, Adams’ Coll.) 5.1; width 3.25, alt. 1.3 mm. 
Type locality Jamaica. Also Kingston, Jamaica. 
Type No. 34825 Walker Coll. Paratype in Adams’ Collec- 
tion. 
