17 



The legs of the 5 th pair (Fig. 6£, 61) extend almost to the middle of the merus of the 2 nd 

 and are nearly as slender as those of the 4 th pair. Merus 4,9 mm. long, carpus 1,8 mm., propodus 

 3,72 -mm., dactylus 1,06 mm. Merus 13-times as long as wide in the middle, almost 3-times 

 as long as the carpus, which is about 6-times as long as thick at the distal end ; propodus 

 twice as long as the carpus, dactylus about one-fourth the propodus, nearly 3-times as long as 

 wide, somewhat spatuliform and armed at the rounded distal extremity and along the lower 

 margin with setae; the seta at the distal end of the upper margin is the longest of all, twice 

 as long as the dactylus, while the rest gradually decrease in length. Exopodite short, little 

 longer than ischium. 



General distribution: Hawaiian Islands (Rathbun). 



Psathyrocaris VV.-Mas. 



The genus Psathyrocaris W.-Mas., characterized besides by other characters by the 

 extraordinary length of the exopodites of the abdominal appendages, is represented by five 

 species and one variety. Psath. fragilis W.-Mas., the first described species, occurs in the Bay 

 of Bengal and the Arabian Sea, probably also in the Indian Archipelago, for a specimen, 

 captured by the "Siboga" off the south coast of Muna Island, must very likely be referred to 

 this species. A variety atlantica Caull. occurs in the Gulf of Gascony, the only not indopacific 

 locality from which this genus is known. Psath. platyophtkalmus Alcock and Anderson is found 

 in the Bay of Bengal and the Arabian Sea, Psath. plumosa Alcock and Anderson in the Arabian 

 Sea and Psath. infirma W.-Mas. in the Andaman Sea. Psath. hawaiiensis Rathb., the 5" 1 and 

 last species, finally, has been taken in the vicinity of Modu Manu, one of the Hawaiian Islands 

 and situated close to the northern tropic. 



As regards the vertical range, it must be observed that the specimen of Psath. fragilis 

 from off the south coast of Muna Island was captured at the greatest depth, namely of 1030 

 fathoms, but this species has also been taken at 172 and at 609 — 620 fathoms in the Arabian 

 Sea, in the Bay of Bengal at 240 and at 609 fathoms. The three other species that occur in 

 the Indian Ocean north of the Equator, have been found at depths varying between 405 and 

 902 fathoms, Psath. hazmiiensis at 876 fathoms, while the variety atlantica was taken by the 

 "Caudan" at 437 fathoms. Psathyrocaris W.-Mas. proves thus to be a truly deep-sea genus. 



1. Psathyrocaris fragilis W.-Mas. 



Psathyrocaris fragilis J. Wood-Mason, Ann. Mag. Nat. Hist. Ser. 6, Vol. XI, Febr. 1893, 



p. 171, PI. X, XI. 

 Psathyrocaris fragilis A. Alcock, A descr. Catal. Indian Deep-Sea Crust., Calcutta 1901, p. 69. 

 Illustrations of the Zoology of the Investigator, Crustacea, PI. Lil, fig. 5. 



Stat. 208. Sept. 22. 5°39'S., I22°I2'E. Off the south-coast of Muna Island. 1886 m. Bottom 

 solid green mud. 1 specimen. 



Unfortunately this specimen is much mutilated, the carapace partly folded and wrinkled, 

 the antennular and antennal flagella, like the legs, wanting, the eye-peduncles, finally, are 



SIBOGA-EXrEUITIK XXXIX a 3 . 3 



