HANSEN: THE ISOPODA. 123 



more or less distinctly separated. Pleural plates not developed. The pleopods 

 quite soft, of medium size, decreasing conspicuously in size from before back- 

 ward and attached to the lateral margin ; each pleopod consists of a short 

 peduncle and two lamellar oblong rami; the outer ramus much larger than 

 the inner one. The uropods biramous ; the outer ramus a little smaller than 

 the outer of the fifth pleopod, the inner ramus very short, almost rudimentary. 

 The pleopods are curled to such a degree that it would have been impossible 

 without much construction to draw a sketch of the abdomen. 



b. Male. 



The body is a little more than three times longer than broad, and from the 

 fourth thoracic segment it decreases in breadth towards both ends (Fig. 2). 



Head. The dorsal surface rather convex ; the median portion of the anterior 

 margin almost straight. No eyes. The frontal border bent slightly do^vnwards 

 (Fig. 2 a). The antennulse rather short, 3-jointed ; the basal joint tolerably 

 thick, and partly overlapped by the rostrum ; the second joint slender and 

 rather short, the third very small. The antennae comparatively long, 7-jointed; 

 the four proximal joints of about the same length, but decreasing much in 

 breadth from the rather thick basal joint to the fourth one ; the fifth joint is 

 sh(jrt and very slender, the two last joints exceedingly small. The mouth 

 forms a rostrum which, when seen from below, is triangular, considerably de- 

 pressed and directed forward, reaching almost to the frontal margin of the 

 head. The hypopharynx is very large, and just outside it is seen the very 

 oblong lateral part of the labrum (cZ), the median part of which is concealed 

 by the hypopharynx ; at first I believed that these oblong organs were the 

 mandibles, but a closer examination gave the result mentioned, while the man- 

 dibles, being needles with browTi apex, were discovered within the rostrum. 

 Maxillulse are not observed ; the maxillae (f) are small semicircular lobes lying 

 considerably behind the posterior edge of the labrum. The maxillipeds (cf) 

 are short, extremely slender, almost styliform. 



Thorax. The segments are rather conA'ex, the incisions between them com- 

 paratively broad and very deep ; the lateral margins are much curved when 

 seen from the side. The legs increase considerably in length, and very much 

 in thickness, from the first (Fig. 2 h) to the fifth pair (Fig. 2 c) which is robust, 

 with the hand very large ; the two posterior pairs again decrease somewhat in 

 size. The terminal margin of the hand is deeply concave, thus differing con- 

 siderably from the preceding forms. 



Abdomen. It occupies scarcely one fourth of the length of the animal ; it is 

 narrower than the last thoracic segment, shortly ovate in outline, without the 

 slightest rudiment of segmentation or abdominal feet; both the ventral and 

 especially the dorsal surface are very convex. 



Size. Uncommonly large, being 7 mm. long, and 2.3 mm. broad. 



Habitat. The branchial cavity of Ghjphocrangon spinulosa Fax., from Station 

 3424 (Lat. 21° 15' N., Long. 106° 23' W.), 676 fathoms, 1 female with its 

 male. 



