5" 



CRUSTACEA MALACOSTRACA. III. 



31. Dendrotion spinosum G. O. Sars. 

 (PI. IV, figs. 2 a — 2 c.i 

 1872. Daulrotion spinosum G. O. Sars, Forh. Vid. Selsk. Christiania for 187 1, p. 273. 

 ! 1897. G. O. Sars, Account, II, p. 116; PL 49. 



Four specimens are to hand, viz. three full-grown females, one of them with marsupium, and a 

 probably adult male. The material, though rather mutilated, enables me to give some additions and 

 corrections to Sars' description and figures, and, besides, to point out characters of specific value. 



The processes bearing the antennulse and antenna; are in my specimens longer than shown by 

 Sars, being more than twice as long as broad (fig. 2 a|. The antennulse are somewhat less elongate 

 than in the next species; the basal joint is very long, but yet, according to Sars' figure, not half as 

 long as the last peduncular joint of the antennae; the flagellum is 9-jointed in a full-grown female. — 

 The anteunse have the peduncle 6-jointed, but the first joint is short and not visible from above, being 

 overlapped by the basal part of the antennula; according to Sars' figure second peduncular joint is 

 not fully one-third as long as the fifth; fifth and sixth joints are extremely long, the sixth longer than 

 the fifth and somewhat longer than the flagellum, which consists of 16 joints. 



The thoracic segments show features of interest. The first segment at each side feebly pro- 

 duced into a low antero-lateral protuberance terminating in a very long, thin process (figs. 2 a — 2 b), 

 and at the lateral part of the front margin of the segment is seen the coxa, which is produced in a 

 rather short epimeral process [rp). Second to fourth segments each produced on the side in a somewhat 

 thick protuberance somewhat less long than, or fully as long as, thick, and bearing the coxa, the 

 anterior margin of which is visible from above at the end of the front margin of the process; just 

 behind the coxa the thick protuberance terminates in a very long, slender process; the whole structure 

 of the three segments is in the ovigerous female more similar to that found in the next species (shown 

 in fig. 3 a) than to the figures of Sars, and in specimens without marsupium the structure is almost 

 as on fig. 3 a, excepting that the lateral protuberances are a little shorter. The processes terminating 

 the protuberances of the four anterior segments are all long, those on second and third segments 

 longer than the others, but conspicuously shorter than the breadth of the head; furthermore they have 

 no granules, are straight, slender, and distinctly tapering to near the end (fig. 2 b), which is slightly or 

 a little thickened, cut off transversely, but with three or four minute or nearly obsolete teeth on the 

 margin, and the end has a very long, strong seta (fig. 2a); the first pair of processes have, besides, a 

 similar seta on the upper side somewhat from the base, while the three other pairs possess the last- 

 named seta and, besides, two or three setae placed more proximally on the process or at the end of the 

 protuberance. The surface of these segments is furnished with a number of similar very long setae, 

 each inserted on a more or less elevated small foot; first segment has only one pair of such setae 

 situated somewhat from the middle near the posterior margin, while second and third segments have 

 four or five pairs placed in a row near the posterior margin and off the base of the protuberances; 

 fourth segment has two or three pairs along the posterior margin and, besides, two pairs in a trans- 

 verse line before the middle of the segment. 



The three posterior segments (fig. 2 cl differ much from the others. Each is produced into a 



