22 ACADEMY OP NATURAL SCIENCES 



near the tip on the anterior edge; origin [79] of the anterior 

 ones, armed behind with a large acute spine. 



Rather common in forests, and frequently found attached to 

 different animals. 



8. I. FUSCOUS [fuscus]. — Body fuscous, ovate, punctured ; 

 tergum with a few black, obsolete lines, and a profoundly in- 

 dented subniarginal line, posterior marginal impressed line none ; 

 no distinct thorax ; edge rounded ; head, posterior edge recti- 

 linear, angles not prominent beyond the rectilinear edge ; eyes 

 not visible ; palpi suboval, terminal joint rather longer than 

 the preceding one. 



Cabinet of the Academy. 



A common species. 



Genus HYDIIACHNA Miill. Latr. 



Rostrum advanced, conic; mandibles none; palpi projecting, 

 terminated by a moveable appendage : body subglobular ; feet 

 natatory. 



H. TRIANGULARIS. — Body white ; eyes two, sanguineous ; 

 tergum with a black triangular spot near the eyes, posterior por- 

 tion black, with a white dorsal line terminating in the cloaca. 



The specimen, from which this portion of a description was 

 taken, I found in Unio cariosus, in which, possibly, it had ad- 

 ventitiously effected a lodgement. [80] 



Genus LIMNOCITAEES Latr. 



Rostrum hardly prominent ; palpi incurved, simple ; mandibles 

 none ; feet natatory. 



L. EXTENDENS. — Body ovate, red, minutely lineated ; tergum 

 with a few indented points ; beneath, origin of the feet paler red ; 

 feet, second and third pair ciliate with very fine and long hairs, 

 posterior pair destitute of cilia. 



Length nearly three-twentieths of an inch. 



A common species, inhabiting stagnant pools, &c., in forests, 

 and shady places. The posterior feet being destitute of ciliae, 

 are only useful in walking; when the animal is swimming, they 

 are extended behind, without distinct motion. The eggs are 

 globular, surrounded by a white gluten, and are deposited on 

 almost any object indifferently, from two hundred to three hun- 

 dred in number, arranged somewhat symmetrically in parallel, 



[Vol. II. 



