136 



CRUSTACEA MALACOSTRACA. III. 



88. Munnopsurus longipes Tattersall. 

 (PI. XII, figs. 6 a— 6 b). 



1905. Eurycope longipes Tattersall, Isopoda, p. 30 and 75; PI. X, figs. 1 — 8. 



Tattersall has published an elaborate decription with figures of this species. He also pointed 

 out differences between it and M. giganteus, but some points may be added, and a view of the main 

 differences may be useful. Of M. longipes I have only a single adult specimen, a male, but there is 

 probably no sexual difference worth mentioning in any organ excepting the abdominal operculum. 



In M. giganteus the antennulce are less than half, in M. longipes considerably more than half, 

 as long as the body. In M. giganteus the first pair of legs, when stretched backwards, do not reach 

 the middle of the abdominal operculum; their second joint is about as long as the sum of fifth and 

 sixth thoracic segments and somewhat shorter than fifth joint, which is conspicuously thicker towards 

 the base than at the end, and at least twice as long as the sixth; in M. longipes this pair are con- 

 spicuously more slender and reach to the posterior end of the abdomen, while their second joint is 

 very conspicuously longer than the sum of fifth and sixth thoracic segments, and only a little shorter 

 than, or as long as, fifth joint, which is scarcely thicker at the base than near the distal end, and 

 considerably less than twice as long as the sixth. — In M. giganteus the abdomen is broader than 

 long, and as long as the three posterior thoracic segments combined; in At. longipes it is produced back- 

 wards, somewhat longer than broad, and conspicuously longer than the three posterior thoracic seg- 

 ments combined. - - In M. giganteus the median lamella of the male operculum tapers feebly near the 

 end, and the end of each half is divided by a deep incision into two lobes, the outer almost as large 

 and nearly as long as the inner; in M. longipes the median lamella tapers posteriorly much (fig. 6 b) 

 to a little from the end; each half terminates in a short and broad, rounded lobe, and at the outer 

 base of this lobe a somewhat small, triangular and acute tooth is seen. — Finally it may be mentioned 

 that in M. giganteus the molar tubercle on the mandibles is low, in M. longipes much higher (fig. 6 a); 

 in At. giganteus the maxillipeds have second and third joints of the palp considerably broader in propor- 

 tion to length than in M. longipes (comp. my fig. in "Dijmphna-Togtet" with Tattersall's fig. 5), while 

 the difference in the shape of sixth joint mentioned by Tattersall must be merely accidental. 



As my specimens of At. longipes have lost most of the antennae and thoracic legs excepting 

 first pair, there may exist unknown differences between M. giganteus and M. longipes in these appendages. 



Length of the best male i8 - 2 mm. — The other specimen is only 4-3 mm. long, and differs from 

 the large specimen especially in the shape of the end of the median opercular lamella, but supposing 

 that this difference and the somewhat more clumsiness of the preserved second joint of first legs are 

 due to age, I venture to refer it to the present species. 



Occurrence. Taken by the "Ingolf" at a deep station in the warm area. 



Davis Strait: Stat. 36: Lat. 6i°5o' N., Long. 56°2i' W., 1435 fath., temp. 1-5°; 1 spec, (large d")- 



The "Th or" captured the above-mentioned small male in the warm area. 



South-West of the Fseroes: Lat. 6i°i5' N., Long. 9°35' W., 463 — 515 fath.; 1 spec. 



Distribution. Some specimens taken in tow-net on trawl or dredge at two places west of 

 Ireland, 350 and 454 fath. (Tattersall). 



