1902.] CRUSTACEA OF THE " SKEAT EXPEDITIOX." 375 



29. DiCHELASPis EQUINA, sp. nov, (Plate XXXY, figs. 7-7 d.) 



Log. Trengganu, 



Hah. Bases of antennules, antennje and legs, and posterior 

 border of carapace of N'eptunus {Amphitrite) gladiator. 



The carina in this species is formed of two pieces — a quite 

 short basal portion, and a much longer tergal portion, each of 

 which abuts closely on the other by a small median tooth ; these 

 two pieces can be separated readily by caustic potash. In the 

 basal portion the base, embedded in the peduncle, is somewhat 

 widened and forked, but the prongs of the fork are not very 

 prominent ; the tergal poi-tion, quite narrow where it abuts on 

 the basal, gradually widens towards its distal end which is squarely 

 rounded. 



The scutum consists, as usual, of two parts, connected by a 

 bridge of tissvie semicalcified on its occludent side, completely 

 calcified on its basal side (fig. 7 d). The occludent segment is 

 neaidy twice as long as the basal (= 5'25 mm. : 3 mm.) and has 

 its apex rounded ; the basal segment is twice as broad as the 

 occludent at the middle of its length, three times as broad along 

 its basal margin, and is pi'oduced at its rostiul angle into a blunt, 

 almost tooth-like process, forming the half-bridge of calcified 

 tissue mentioned above. General shape subtriangular, with 

 rounded angles ; its basal and tergo-lateral margins are somewhat 

 convex, the occludent somewhat concave. 



The tergum has i-ather the shape of the head and neck of a 

 horse with forwardly-directed ears (whence the specific name) — 

 the base of the neck lying between the apices of the occludent 

 segment of the scutum of the carina ; the top of the head forming 

 the upper, the back of the neck the lower carinal margin ; a.nd 

 the snout forming a strong tooth projecting in the direction of 

 the scutum, and the forehead forming the occludent margin. 



The 1st cirrus lies close to the 2nd, but yet a little more distant 

 than the rest are from each other ; the rami of each of all the 

 cirri are equal ; the 1st cirrus is only a little more than half the 

 length of the 6th. The caudal appendage is as long as the 

 1st joint of the pedicel of the 6th cirrus ; it carries hairs at its 

 apex, of which the longest are about half the length of the joint, 

 and also distant bundles of 2-3 longish haii's along the outer 

 margin. The penis is just shorter than the 6th cirrus, thick, but 

 tapering suddenly at the tip, with an excavation at the base, at 

 the distal angle of which excavation is a blunt tooth-like promi- 

 nence, nearly as high as the excavation is deep ; this prominence 

 is set within a shallow hollow within the excavation. The penis 

 also, besides the hairs at its tip, bears along its length scattered 

 hairs, some short and stifi", others long and more flexible ; lings 

 very distinct. 



The palpi are bluntly conical, with longish hairs at the tip. 

 The mandible has five teeth, the one at the inner angle being the 

 strongest, and the one at the outer angle very small and blunt, 

 lying close to the 4th tooth at its outer base. 



