REPORT ON THE CRUSTACEA MACRURA. 519 



the former of which has only a point and the latter has also one which is directed out- 

 wards and backwards. 



The telson is long and very rigid and has a distinctly controllable movement. It is 

 connected with the sixth somite by a peculiar articulation, a small laterally projecting 

 process of the telson being enclosed in a deeply embayed hollow in the posterior margin 

 of the sixth somite ; this kind of articulation also exists in the two preceding somites. 

 The movement of these as well as that of the telson is such that by a very slight con- 

 traction of the muscles they can be held in a rigid position, and this is undoubtedly 

 voluntary. The power which these animals have of suddenly and rapidly darting 

 backwards makes this sword-like telson a very formidable weapon. Our specimen corre- 

 sjJonds in many points with Glypkocrangon spinicauda, which Professor A. Milne- 

 Edwards has described as having been taken near the island of St. Kitts at a depth of 

 about 250 fathoms. It may readily be distinguished by the absence of a second tooth 

 on the hepatic region, as also by the absence of a tooth on the branchial region at the 

 anterior extremity of the upper lateral carina, which terminates posteriorly to the cervical 

 fossa. 



The female specimen taken at Station 173 varies slightly from the type, but I 

 consider it to belong to this species. It corresponds in all points, excepting that the 

 details are not so well defined, the tuberculation is less conspicuous, the teeth not so 

 strong, and the extremities of the rostrum and of the telson not so decidedly curved ; 

 in length it is a little shorter, and there is a minute tooth about one-third the length of 

 the scaphocerite from the base, which is not so conspicuous in the typical specimens. 



At Station 171 there was brought up a very broken fragment of a carapace, which, 

 from the stoutness of the outer flagellum of the first pair of antennae, I take to be that of 

 a male specimen of this species. It is much smaller than the type specimen — judging 

 by the size of the carapace it could scarcely be 50 mm. in length — and it differs from 

 the latter, which is a female, in having the teeth on the frontal margin smaller in pro- 

 portion to that on the hepatic region. 



Glypkocrangon hastacauda, n. sp. (PI. XCIII. fig. 5). 



Carapace slightly tomentose ; smooth between the carinse ; all the carinse smooth 

 except the two dorsal ones, which are imperfectly dentate. Orbital tooth large, flat, long 

 and sharp pointed ; tooth on the fronto-lateral angle not so long as the orbital. Hepatic 

 tooth small. The two lateral carinas on each side terminate anteriorly in a minute 

 denticle just behind the cervical fossa. 



Rostrum nearly as long as the carapace, armed with two teeth on each side. 



Pleon furnished with an interrupted carinas in the median line. 



Ophthalmopoda orbicular. 



