A New Genus of Fresh-ivater Isopoda. 127 



of the peraeon. The lateral margins of the cephalon and each 

 succeeding segment is fringed by a x*ow of short stiff spinules. 

 The Cephalon is small, transversely suboval, subequal in length 

 to the succeeding segment, with the anterior margin slightly 

 produced and bluntly rounded between the antennae. The 

 lateral margins are slightly expanded. The Eyes are not formed 

 nor is there any appearance of lenses nor pigment, but in some 

 specimens there is a very slight appearance of two round areas, 

 indicated by somewhat lighter colour, where the eyes would 

 normally be, but it is doubtful if these are vestigial remnants of 

 former functioning eyes. The Peraeon (mesosome) has the seven 

 segments each clearly defined, slightly dorso-ventrally arched, and 

 the lateral margins of each are simple, bluntly rounded, and cover 

 the coxa of the appendages. The Pleon (or metasome) is of normal 

 form, very large, longer than its greatest breadth, and as long as 

 the four preceding segments combined. The posterior margin 

 between the uropods is very slightly produced and rounded. The 

 lateral and posterior margins are entire and fringed with short 

 spinules. 



Superior Antennae (Fig. 1). — The superior antennae reach 

 somewhat beyond the middle of the fifth joint of the inferior 

 antennae. The basal joint is very stout, the second and third 

 much narrower, and the remaining portion — the flagellum — is 

 composed of three or four joints. The distinction between 

 flagellum and peduncle is, however, not clearly marked. The 

 terminal joint is richly tipped by so called " olfactory " and 

 feathered " auditory " sensory setae ; occasionally also from other 

 parts arises a feathered sensory seta. 



Inferior Antennae (Fig. 3). — The inferior antennae measures as 

 long as the body and uropods combined. It is fixed under the 

 arched frontal margin of the cephalon. The peduncle, which is 

 composed of six joints, is about twice the length of the superior 

 antennae ; the first joint is subquadrate, the second transverse, 

 the third as long as the first two combined, and mesially, from 

 the outer margin, arises a well marked cylindriform appendage, 

 tipped by long setae. The fourth joint is short and turned 

 obliquely outwards ; the fifth is slightly longer than the first four 

 combined, and, close to its attachment to the fourth joint, the 

 outer margin is slightly produced to form, in optical section, an 



