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. 



Pachy chilus glaphyrus immanis (Morelet). Common on the 

 soft mud at the mouth of the streams. 



Pachyckilus 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 riiginosus (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. 



