15 i 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 1873.* 



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 seta? ; the posterior portion is 

 almost or quite naked (pi. XXI., fig. 9). 



The rostrum (pi. 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 (pi. 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 seta?. 



Integument. — 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. 



