6 CRUSTACEA MALACOSTRACA. III. 



which is twice as broad as most of the segment, and slightly or somewhat narrower than the anterior 

 segments. 



First pair of legs (fig. i g) slender; fifth joint more than three times as long as deep, with two 

 verv long, nearly setiform spines and more distally a somewhat short, thin spine on the lower margin; 

 sixth joint somewhat shorter and a little thinner than the fifth, with two somewhat short spines beyond 

 the middle of the lower margin. The six other pairs of legs very long and very slender, without 

 granulations, but with some very short and thin spines on fifth and sixth joints; second joint of fourth 

 pair reaches, when stretched backwards, scarcely to the end of the corresponding joint of fifth pair. 



Abdomen (fig. i h) about as long as broad or slightly longer than broad, and about as broad 

 as the leg-bearing part of fifth thoracic segment; the major part of each lateral margin is rather convex 

 and, besides, serrate from triangular granules; posteriorly, where this serration terminates, alow emar- 

 gination is found, and the posterior margin between the uropods is moderately protruding and nearly 

 semicircular. — The median lamella of the operculum, when seen in its natural position (fig. i i), tapers 

 much from somewhat from the base to near the narrow end, but removed from the animal it is seen 

 (fig. i k) that a rather broad part of more than the distal half of the lamella has been overlapped by 

 the two lateral plates of the operculum. The copulatory process is short (fig. i 1), not reaching the 

 end of its pleopod. — The uropods are triangular, very short, not reaching beyond the end of abdomen. 



Length of the three largest males (from Stat. 36, 38 and 116) 5 mm. 



Female. Body (fig. 1 m) anteriorly much stouter than in the male, about five and a half times 

 as long as broad across the first thoracic segment, the processes not counted. The integument as in 

 the male. — The antennulee (fig. 1 n) when directed backwards reaching about to the posterior margin 

 of third segment; second joint only half as long again as the four distal joints combined. — Antennae 

 about as long as the thorax; sixth peduncular joint cylindrical, very slender and somewhat longer than 

 the fifth; flagellum almost as long as the two distal peduncular joints combined, 17-jointed. 



The thorax with the same two pairs of processes as the male, but the first pair are much 

 smaller (fig. 1 n), less than half as long as the breadth of its segment, while the second pair are more 

 than half as long as first pair. The four anterior segments are proportionately considerably broader 

 than in the male, while the fifth segment is less elongate, five or six times as long as its shortest 

 breadth, and with the leg-bearing terminal part considerably narrower than the three anterior segments. 

 — The legs about as in the male. 



The abdomen (fig. 1 o) conspicuously longer than broad, and narrower than the terminal part 

 of fifth thoracic segment; its median longitudinal area is, as in the following forms of the group, 

 broader than in the male, but in other respects the abdomen is nearly as in this sex. — The operculum 

 (fig. 1 p) about as long as broad, with the basal margin very flatly convex, while its distal half has 

 the margin semicircular. 



Length of females with the marsupium rudimentary or wanting 4-5 mm. 



Remarks. H. quadrispinosus is easily distinguished from the other forms of the genus by its 

 two pairs of very conspicuous processes, and especially by the fact that the second pair are situated 

 on the third segment, while fourth segment has no processes; besides, the shape of the abdomen is 

 characteristic, differing much from those in the four following species. — Sars established the species 



