CRUSTACEA FROM THE ' CHALLENGER ' EXPEDITION. 51 



no lateral compression as in Astacus or in Palinurus. The cephalothorax exceeds in 

 width half of its length ; and the abdomen too is very flat. The whole animal, being a 

 male, has a length of 120 millims.* (Plate XIII. fig. 1.) 



The cephalothorax has a length of 60 millims. by 33 in width at its base. Its upper 

 lateral edges are very sharp, and formed by a series of lateral spines, those of the under- 

 side, however, rounded. The whole cephalothorax, owing to this configuration of the 

 carapace, is square, the upper surface being wider than the under one, and somewhat 

 convex, the side parts being not rounded as in Astacus but perfectly flattened ; also the 

 upper surface forms a square, the angles of which are terminated anteriorly by two 

 spines, and are posteriorly rounded. A line of spines runs longitudinally through the 

 midst of the carapace, and divides it into two portions, being terminated anteriorly by 

 a sharp spine. The lateral spiny edges are divided by small but clearly perceptible 

 fissures into four portions, the first of them containing 8, the second 5, the third 5, 

 and the last 6 larger spines. A deep transverse sulcus divides the carapace into an 

 anterior and a posterior portion, which by secondary elevated lines are again divided 

 into several regions, which we might call the stomachal, hepatic, lateral, cardiac, and 

 branchial regions, each of which will be easily seen in the drawing (fig. 1). The inner 

 borders of the carapace of the under surface are perfectly smooth ; and the rounded exte- 

 rior edges of the same surface are covered by a fringe of long and beautiful hairs. The 

 whole carapace is covered by very small spines, all directed forward, giving it a certain 

 likeness in appearance to the well-known chagrin of the sharks. 



The eyes are entirely wanting ; nor is there, as in Astacus zaleucus, any place left open 

 where you might expect to find them. 



Immediately underneath the frontal edge of the carapace we find in a prominent place 

 the wing-like expansions of the joints, funiculi antennarum anteriorum. They are (espe- 

 cially at the inner side) densely covered with hairs, and very closely approach each 

 other. The funiculus consists of three joints, and has a length of 10 millims. Its in- 

 ternal flagellum, consisting of very many rings, has a length of 65 ; while the external 

 is very short, being only 10 millims. in length. On the same line with the inner antennae 

 and close to them, are the outer ones, the funiculus of which is a little more elongated, 

 and consists equally of three joints (12 minims, in length). The squamiform appendage 

 is very small (8 millims. in length by 2 in width), lancet-shaped, and inserted at the base 

 of the first joint. The flagellum is 60 millims. in length. 



The opening of the mouth is angular (fig. 4) ; and you find above its rejected border a 

 small tuft of hairs. I could not find any labrum. The mandibulce, covering nearly the 

 whole opening with their strong manducatory processes, have behind these a strong and 

 hairy palpus (fig. 5,pm), and at their base the two slender organs (fig. 5, lab) which repre- 

 sent the labium or under lip. The first maxilla (fig. 6 a) shows a very small rudiment of a 

 flagellum (fl), which in the second maxilla (fig. 6 b) attains so considerable dimensions. 



The maxilliped has two manducatory processes (fig. 7), a palpus (fig. 7, p), and a 

 flagellum, which is divided into two portions, the upper one (fl 1 ) being attached to 

 the palpus, and the under one to the base of the maxilliped (fl 2 ). 



* This description refers to the larger of the two males procured. 



H 2 



