154 Transactions.— Zoology. 
very largely developed; and I have also had two specimens in which ecdysis 
had evidently taken place some little time before their capture and yet the 
gastroliths were very largely developed in both. The conclusion I have 
therefore to draw is that the development of the gastroliths in Paranephrops 
differs from that in Astacus. 
Paranephrops setosus was first described by Professor Hutton in 1878.* 
The various parts mentioned in his description will be more minutely 
described in their proper places, but there is one small point that needs 
amending. This is with regard to the hairs on the great claws. These 
are described as ‘distant long stiff hairs, the tips of which are often split,” 
but these are in reality small tufts of hairs each containing from six to 
twelve separate hairs. In each tuft there are two kinds of hairs, one naked 
and jointed the other plumose and without joints (see under integument). 
The hairs in each tuft become closely united together in dried or spirit 
specimens, and thus appear very like single stiff hairs, and this is no doubt 
the cause of the mistake. 
The thoracic sterna in Paranephrops setosus are quite narrow, and those 
corresponding to the first four pairs of ambulatory legs are firmly united 
together, while that of the last thoracic segment is separate, so that this 
segment is more or less movable. In this Paranephrops resembles Astacus 
and differs from Palinurus. 
The inferior edge of the pleura of the third abdominal somite is 
rounded; the anterior portion is slightly more convex than the posterior 
part and is fringed with several plumose sete; the posterior portion is 
almost or quite naked (pl. XXI., fig. 9). 
The rostrum (pl. XIX., fig. 9) has been already well described by Professor 
Hutton. The end projects slightly upwards. On the under surface there 
are two large, median, rather blunt teeth. These teeth and likewise the 
four teeth on the two sides are subject to some variation, for in one speci- 
men there were four teeth on one side and only three on the other, and in 
another specimen there was only one tooth underneath. 
The telson (pl. XX., fig. 4) consists of a single piece, there being no 
transverse hinge. On each side about one-third of its length from the end 
there is a strong single spine. The extremity is rounded and fringed with 
plumose sete. 
Inteyument.—The integument is completely calcified throughout, except- 
ing such portions as must necessarily remain soft and flexible to allow of 
the movements of the various parts of the body. The telson and the 
appendages of the sixth abdominal somite are hard and not semi-membran- 
aceous as in Palinurus. The hardest parts are the anterior portion of the 
* Ann, and Mag. Nat. Hist., ser. 4, xii., p. 402. 
