VI 124 Carl Zimmer. 



The genus is obviously different from all other hitherto known Mysidacea 

 in having the last thoracic segment (at least in the female) very elongated ; dorsally 

 it is not much shorter than the two first abdominal Segments taken together whilst 

 ventrally it is even considerably longer than dorsally; the seventh pair of thoracic 

 legs are inserted at its front margin. The carapace is tolerably short, deeply 

 incised posteriorly, so that the central portion of the penultimate thoracic segment 

 is uncovered; its lateral wings reach a little beyond the front margin of the last 

 segment. The left mandible has the pars incisiva well developed, its lacinia 

 mobilis has a large and strong cuspis incised at the end, whilst behind this 

 there is only a pair of weaker setse; the pars molaris is slightly marked, small 

 and weakly developed; the Avhole margin from the base of the cuspis to the 

 posterior end of the pars molaris is furnished with fine hairs. The lobe of the 

 second Joint of the maxillae is rounded, with no protuberance, that on the 

 third Joint is cleft; the last Joint of the palp unusually long, and the greater 

 part of the under side of this Joint and of the lobes are densely covered with 

 hairs. The second Joint of the maxillipeds is long with a small but distinct 

 lobe, the third very short with a similar lobe, the 4 following joints with 

 inconsiderable difference in length but decreasing outwards in breadth, so that the 

 two last are fairly narrow. The first thoracic leg has the second Joint in 

 the form of a large plate as broad as long; the rest of the leg is slender, the 

 sixth Joint somewhat shorter than the fifth, the claw well-developed. The other 

 thoracic legs, which increase somewhat in length from before backwards, are very 

 slender except as regards the second Joint, which is a large and broad plate; 

 the sixth Joint is considerably longer than the fifth without oblique articu- 

 lation, but its shorter distal part is separated as a distinct Joint by a well-developed, 

 vertical articulation ; the seventh Joint and the claw are well-developed. The exo- 

 podite on the thoracic legs has the subbasal Joint large and unusually broad, 

 plate-like (the exopod of the maxillipeds was broken off.) Antennae and tail-fan 

 almost as in Meterythrops," (H. J. Hansen, 1908, Ingolf Exped. vol. 3, 2, p. 104.) 



75. Longithorax fuscus Hansen. 



Fig. 240—243. 



1908. Longithorax fuscus H. J. Hansen, Ingolf Exped. vol. 3, 2, p. 103—105. 



tab. 5 f. la— lo. 



„As there is only the mentioned incompletely developed specimen to hand, 

 only the carapace, eyes, antennal scale and caudal process will be described here, 

 the other characters can be learnt from the description of the genus and the figures. 



The front end of the carapace, seen from above is triangulär, with 

 median angle a little over 90*^, but the very tip is produced in a very small 

 process which is somewhat smaller than the process on the eye-stalks. The eyes 

 are yellowish and moderately small; seen from the side they look downwards 

 a little and occupy the end of the eye-stalks in a flattened arch; seen from 



