86 



It has the outline of A. Deshaysii, but is much smaller, more 

 slender, more numerously ribbed, less acute posteriorly. 



Cyclas egregia. T. ventricosa, transversa, oblonga, sub- 

 equilateralis, concentrice tenui-lirata ; umbonibus parum elevatis, 

 tumidis; epidermide viridi-corneo, fusco-zonato ; plerumque C. 

 cornea similis. Long. £; alt. | ; lat. 4- poll. Hab. New South 

 Wales ? 



It is larger, more rounded in outline, and more globose in 

 form than C. cornea. The epidermis is less glistening, of a 

 deeper green, and exhibits no traces of radiations. The liga- 

 ment is shorter and more prominent. The beaks, hinge, and 

 furrowing are nearly the same in both. 



Cyclas patella. T. parva, tenuis, rotundato-ovalis, lenticu- 

 laris, modice cavata, concentrice exiliter sulcata, epidermide 

 luteo-viridi induta ; umbonibus medianis, rotundatis, haud eleva- 

 tis : intus lactea : cardo dentibus duobus minutis cardinalibus 

 instructus ; dentibus lateralibus remotis, validis. Long. 4 ; all. £ ; 

 lat. } poll. Hab. Oregon. 



This is to be compared with C. cornea on account of the 

 peculiar rounded form of the dorsal region, the umbones not 

 rising so as to interfere with the general outline. The cavity of 

 the beaks is still more shallow, the sulcation coarser, and the 

 color yellowish rather than green, and on the whole the shell is 

 more dense and larger. 



Cyrena debilis. T. parva, tenuis, transverse ovata, postice 

 ampliata et subtruncata, sub-equilateralis, concentrice liris con- 

 fertis, sub-reflexis arata ; epidermide nitido, superne olivaceo 

 induta ; umbonibus parum elevatis, erosis, absque lunula : intus 

 violaceo-albida ; dentibus cardinalibus inconspicuis, dentibus 

 lateralibus elongatis, striatis. Long. t 6 q ; alt. -^j ; lat. £ poll. 

 Hab. New Holland ? 



Most like C. pusilla, but has no areola in front of the beaks, is 

 less orbicular, and somewhat larger. In general it resembles a 

 Cyclas. 



Anodon glauca. T. transversa, elongato-ovata, ventricosa, 

 antice rotundata, postice oblique rotundato et costa obliqua sub- 

 marginali munita ; margine dorsali arcuato ; margine ventrali 



