THE NAUTILUS. 47 
Ampullaria flagellata tristrami C. & F. Marshy places and 
along the border of the lake, among the rushes on which the 
white egg-masses were quite numerous a little above the surface 
of the water. 
Ampullaria flagellata lattrei C. & F. On rocks near San Felipe. 
Pachychilus glaphyrus immanis (Morelet). Common on the 
soft mud at the mouth of the streams. 
Pachychilus glaphyrus obeliscus (Morelet). The most plentiful 
Pachychilus in the lake. They are more attenuate and smaller 
than the closely related immanis. 
Pachychilus lacustris (Morelet). These appear more like a 
smoother form of P. obeliscus, and do not agree with P. lacustris 
from Lake Amatitlan, from which they differ in fewer and flatter 
whorls, and the suture not as deep. 
Pachychilus pyramidalis (Morelet). Plentiful in clear streams, 
often concealed in lodgments of brush and leaves. On account 
of its size and clean living it is preferred for food. They are 
cooked in stews or soups, croquettes, or roasted. The species 
often reaches three inches in length. 
Pachychilus pottsianus n.s. Found only on two hillsides back 
of Jocolo. 
Potamopyrgus coronatus nicaraguanus Ancey. Plentiful; varies 
from a smooth shell to one with strong striations and prominent 
spines. 
Cochliopa dulcensis Marshall. With the following two species. 
Cochliopa hinkleyi Pilsbry. This small flat species of a size 
that evidently washed through the net in numbers when taking 
the other small species. 
Cochliopa izabal Pilsbry. Common, has some resemblance to 
C. guatemalensis. 
Cochliopa izabal Pilsbry, mutation peristriata Pilsbry. 
Hemisinus ruginosus (Morelet). Common in places on the 
lake shore. In 1914 one immature specimen was all that was 
found. In 1917 the first were taken in the net with Cochliopa, 
etc. Later while picking up JVephronaias they were noticed 
among numerous Pachychilus and could easily have been passed 
as the young of that genus. Their trail was made by burrow- 
ing instead of crawling on the surface as with other forms. 
