156 Transactions.—Zoology. 
The protopodite of the antenna (pl. XIX., fig. 2) is two jointed. The 
basal joint is small and bears the conical opening of the green gland (99) 
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 surfacé of the protopodite. The exopodite (ew) 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 sete. The base of the 
endopodite is composed of two joints of about equal size, each of which 
bears setze abundantly on the inner side. Each joint of the flagellum bears 
some of both kinds of sete. : 
` Mandible (pl. XIX., fig. 8).—The protopodite appears to be essentially 
the same as in Astacus. The palp is 8-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 sets. 
In the first maxilla (pl. 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- 
podite (cap) is comparatively small and narrow. Both have their extremi- 
ties fringed with short styliform sete. 
The second masilla (pl. 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 (cap) 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 sete. 
In the first maxillipede (pl. XIX., fig. 6) the coxopodite (cap) and the 
basipodite (bp) are broad thin plates with setose edges; the basipodite 
is considerably larger than the coxopodite. The endopodite (en) is small 
and 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 mawillipede (pl. XIX., fig. 7). —The exopodite (ea) is large com- 
pared with the rest of the limb ; the basal joint is long, thin and fringed 
with sete, the flagellum is very well developed, being as long as the basal 
joint. The coxopodite (exp) is large and broad and bears the podo- 
