18 THE VOYAGE OF H.M.S. CHALLENGER. 



Descnptioii. — The specimen examined is a female, and may be assumed to be nearly 

 full o-rown, since the incubatory lamellas are distinctly perceptible beneath the trunk, 

 though still rather small, and not as yet forming any marsupium. The length, too, of 

 the animal does not exceed 12 mm., and hence this form would appear to be the smallest 

 of the known Lophogastrida^. 



The general form of the body (see figs. S and 9) is comparatively short and thickset, ' 

 resembling on the whole that of Lophogaster, with this difference, however, that the ' 

 anterior division, owing to the strong development of the carapace, appears somewhat > 

 larger when compared with the posterior. t 



Contrary to what is usually found to be the case in Schizopods, the integuments are 

 remarkably firm and highly indurated, giving to the whole body a peculiar rigidity, 

 somewhat resembling the higher forms of Macrura. 



The carapace is of very considerable size, fully equalling in length the tail, if the telson 

 be excluded. It completely covers the whole anterior division of the body in such a manner 

 that none of the segments of the trunk are dorsally exposed. Its surface is rather uneven, 

 exhibiting, more particularly in the upper part, a peculiar rugged or wrinkled aspect 

 (see fig. 8). A distinctly impressed line marks oflF above, as in Lophogaster, a somewhat 

 linguiform dorsal area, terminating about the beginning of the posterior fourth of the 

 carapace. Posteriorly to this area, and laterally, the carapace covers the trunk but 

 loosely, whereas within the area it forms the immediate wall of the body. Anteriorly, the 

 carapace projects as a broad, horizontally extending frontal plate, covering the eyes 

 and a great part of the antennular peduncles, as in Lophogaster. This plate juts out 

 in the middle as a conical process, reaching to the end of the antennular peduncle, and 

 more properly answering to the rostrum. The lateral edges of the frontal plate (the 

 supraorbital spines) form similar processes, though somewhat shorter and more deflexed 

 (see fig. 8). The inferior margins of the carapace are but very slightly arcuate, and 

 terminate anteriorly almost in a right angle. The posterior margin, too, is abruptly 

 truncate, not as usual emarginate in the middle, and the lateral wings of the carapace do 

 not project at all posteriorly. 



The posterior division of the body, or tail, is comparatively short and uaiTow, 

 exhibiting dorsally a similar rugged appearance to the carapace, the median part of 

 every segment being rather convex, whereas at both extremities a distinctly perceptible 

 transverse impression occurs. The epimera are rather small, of an obtusely triangular 

 form, and finely serrated at the posterior margin toward the apex (fig. 16). The first 

 segment has on either side an anteriorly pointing projection, fitting in beneath a 

 short corresponding lateral keel on the posterior part of the carapace when the 

 tail is fully extended (see fig. 8). The last segment is not much longer than the 

 preceding, but rather narrower. It has no trace whatever of the transverse 

 suture observed in Lophogaster, but exhibits posteriorly on either side a strong 



