2 University of Michigan 



SPHAERIID.^ 

 Pisidiitm otlanticum Stcrki. Sixteen specimens from near 

 bank of La Laja, buried in wet humus and leaves at edge of 

 forest pools (H, v, a). The growth-wrinkles on these speci- 

 mens are considerably coarser than is usual in the species. 



PLAXORBID.E 



Plaiiorbis cnltvatus d'Orbigny. One specimen; on roots of 

 water plants, northern corner of Lake Catemaco (H, vii, d). 

 More or less in*^ermediate between this species and P. siuni- 

 chrasti C. and F., this specimen appears closer to the former. 

 It is somewhat higher than typical P.' cultratus, and the cari- 

 nation of the outer lips of the aperture is not quite so acute. 



Plonorbis isabcl "]\Iorelet" Sowerby (1879). 

 P. ycabclciis'.s C. and F. (1879). 



Eleven specimens; 10 from pools in burnt-over area (H, 

 V, b) ; I from rocks in shallow water near shore of Laguna de 

 Catemaco (H. vii, d). A peculiar species, with each whorl 

 extensively enveloping the preceding one. 



Planorbis rctusus Morelet? A single small, broken speci- 

 men, but the growth and spiral riblets are well marked; from 

 lowland forest ponds along La Laja (H, v, a), perhaps drifted 

 in from La Laja itself (H, vii, a). 



Planorbiila orbiciila (Morelet). Two rather small speci- 

 mens; from Laguna de Catemaco (H, vii, d). 



Planorbiila obstructa (Morelet). Five specimens; from 

 lowland forest pools (H, v, a) and pools in burnt-over region 

 (H, V, b). These correspond very well with Crosse and 

 Fischer's figures. 



Planorbiila dciiticns cannarum (]\Iorelet). Nine specimens; 

 from roots of water-])lants. T^aguna de Catemaco (H, vii, d). 



