15(3 Transactions. — Zoology. 



The protopodite of the antenna (pi. XIX., fig. 2) is two-jointed. The 

 basal joint is small and bears the conical opening of the green gland (gg) 

 and just above it a strong spine. The other joint of the protopodite is large 

 and broad and is divided into two parts more or less movable upon one 

 another. There is a strong spine on the outer side at the base of the scale 

 and another on the inside ; and there are three or four other spines on the 

 under surface of the protopodite. The exopodite (ex) is represented by the 

 squame or scale, which reaches beyond the basal joints of the endopodite. 

 Its inner edge is curved and fringed with plumose setae. The base of the 

 endopodite is composed of two joints of about equal size, each of which 

 bears setae abundantly on the inner side. Each joint of the flagellum bears 

 some of both kinds of setae. 



Mandible (pi. XIX., fig. 3). — The protopodite appears to be essentially 

 the same as in Astacus. The palp is 3-jointed but the first two joints are 

 not movable upon one another and the joint between them is somewhat in- 

 distinct. The third joint is freely movable upon the second, it is slightly 

 bent near its proximal end, its extremity is rounded and provided with 

 many seta?. 



In the Jirst maxilla (pi. XIX., fig. 4) the endopodite (en) is better developed 

 than in Astacus ; it consists of a basal joint followed by a short indistinctly 

 segmented flagellum. The basipodite (bp) is pear-shaped while the coxo- 

 poclite (cxp) is comparatively small and narrow. Both have their extremi- 

 ties fringed with short styliform setae. 



The second maxilla (pi. XIX., fig. 5) closely resembles that of Astacus in 

 general appearance, but the scaphognathite (sg) is small compared with the 

 rest of the appendage. The endopodite (en) is small and undivided. The 

 coxopodite (cxp) and basipodite (bp) are lamellar and are subdivided by 

 deep fissures into four portions which are much narrower than the cor- 

 responding parts in Astacus. Their extremities are fringed with setas. 



In the first maxillipede (pi. XIX., fig. 6) the coxopodite (cxp) and the 

 basipodite (bp) are broad thin plates with setose edges ; the basipodite 

 is considerably larger than the coxopodite. The endopodite (en) is small 

 arid consists of a short basal joint and an indistinctly segmented flagellum 

 slightly longer than the basal joint. The basal joint of the exopodite (ex) 

 is long and is followed by a flagellum about as long as itself. The epipo- 

 dite (ep) is a soft membranous plate rounded at the extremity and bearing 

 numerous branchial filaments. 



Second maxillipede (pi. XIX., fig. 7). — The exopodite (ex) is large com- 

 pared with the rest of the limb ; the basal joint is long, thin and fringed 

 with setae, the flagellum is very well developed, being as long as the basal 

 joint. The coxopodite (cxp) is large and broad and bears the podo- 



