158 Transactions.—Z oology. 
finger, each row containing about twelve spines. On the outside there is a 
central row, and also several other spines more or less irregularly placed. 
On the outer edge the dactylopodite bears two rows of spines, six in one 
and four in the other, and there are two small spines at the tip. Each 
finger ends in a.strong spine pointing towards each other, and on the inside 
of the fingers are three or four rounded prominences. There are numerous 
tufts of setzte on most of the joints, but most abundantly on the propodite. 
The four posterior pairs of ambulatory legs are somewhat slender; in all 
except the last the coxopodite bears a podobranchia and a small tuft of 
coxopoditie sete. 
The first pair of abdominal appendages are entirely absent both in the 
male and female. 
The second, third, fourth and fifth abdominal appendages are all alike, and 
are rather simpler than those of Astacus. The coxopodite (pl. XX., fig. 1 
cxp) is very short, and is followed by the long cylindrical basipodite (bp) 
whieh supports the exopodite (ex) and the endopodite (en). In the male 
these are of about equal length, and are imperfectly articulated through 
their whole length, neither of them having an undivided basal joint as in 
Astacus. Their edges are fringed with long plumose sete. In a female 
with the eggs attached under the abdomen the appendages (pl. XX., fig. 2) 
were found to differ somewhat from those of the male. They were much 
slenderer and the exoskeleton was much softer; the endopodite (en) was 
considerably longer than the exopodite (ex), and in both the articulations 
were very indistinct ; the sete were long and did not appear to be plumose. 
In a young female, however, in which the eggs were still in the ovary, the 
abdominal appendages were much more like those of the male, and were 
supplied with plumose sete. 
The appendages of the sixth abdominal somite have the coxopodite (pl. 
"XX., fig. 8, cwp) broad and indistinctly divided into two or three parts. The 
exopodite (ex) is in the form of a broad oval plate divided into two parts by 
a transverse hinge, the basal part ends distally in a row of short spines of 
which the outside one is the longest. The terminal portion is rounded and 
fringed with plumose sete. A median ridge runs from the coxopodite 
through the whole length of the exopodite. The endopodite (em) is of 
similar shape, but consists of one piece only, the median ridge ends in a 
sharp spine at some distance from the edge. 
Respiratory organs.— These differ considerably from those of Astacus, 
and closely resemble those of Astacopsis.* The epipodite of the first maxil- 
lipede is in the form of a broad more or less oval-shaped lamina, the end of ` 
which bears numerous branchial filaments similar to the filaments of the 
* * The Crayfish,” p. 264. 
