344 PROCEEDINGS OF THE ACADEMY OF [May, 
The embryonic shell, of slightly over 2 whorls, is smooth and 
projects nipple-like. The following whorls of the cone are strongly 
ribbed, but the ribs weaken more or less on the cylindrical part, 
so that on the penultimate whorl they are often inconspicuous or 
almost wanting (for brevity called “smooth” in the above tables). 
There is of course complete intergradation in this character, so that 
the classification in the table is more or less arbitrary. The size 
averages larger in shells with 2 or 3 lamelle, but there are exceptions. 
It will be understood that the measurements were based upon shells 
which to all external appearance are adult or old. After a careful 
study of the aperture and lip, I think that it may be accepted as 
certain that the variations in lamella recorded above are not depend- 
ent upon age of the individual. 
At Station 10, on the northern slope of Hacheta Grande Mt., 
a small series was taken. All of them have the whorls of the cylindric 
portion smooth or nearly so, glossy, the cone and the last whorl, 
or its last half, being ribbed as usual. Ten specimens opened measure 
as follows: 
Length 14.2, diam. 4 mm.; whorls 14; axial and basal lamelle. 
Baek zi De 125; 
ce 13, ce 4.4 ce 73 123; “é (74 (a4 “ec 
ce 13 cc AD ce “ce 123; ‘é “ec (74 “ce 
“cc 12:9, (a3 4 ce “ce 123; (a9 cc 79 ce 
git FS yA le i ee ‘¢ 12; axial lamella only. 
cc 115, ce 4 “ce ce 12; 73 ce ce 
“ce Tt.5; (73 4 ‘ce ce 12; (73 73 ce 
cc 113; 73 3 9 (79 ce 113; (74 (73 ce 
cc 10.3, a9 3 3 cc a9 113; (74 cc “ 
This lot, by the size of some individuals and the large number 
(50%) of bilamellate example, is intermediate between crosse: and 
mearnsi, as it also is in the elevation of the station. It has a feature 
of its own in the smooth median whorls, parallelled, however, by 
some individuals of crossei from the mountain top. None of the 
mearnsi seen are so smooth. 
ZONITIDA. 
Vitrea indentata umbilicata (CkIl.). 
Stations 3, 5 and 8. 
Zonitoides minuscula alachuana (Dall). 
Stations 8 and 11. 
FERUSSACIDA. 
Cochlicopa lubrica (Mill.). 
Station 8. Scarce. 
