158 



CRUSTACEA MALACOSTRACA. III. 



MunnOpSOJdeS Tattersall. 



Description. Body with the anterior thoracic segments and especially third segment very 

 much broader than the three posterior segments, which are very slender. - First joint of the anten- 

 nulae (PL XIV, fig. 2 f) very broad, with the insertion of second joint lateral, and the first joint pro- 

 duced considerably beyond that insertion. Antennae about as in Mtmnopsis. - Mandibles reduced; 

 without molar process or palp ; the incisive part of left mandible (fig. 2 c) showing a terminal feeble 

 emargination as a rudiment of a division into teeth; the lacinia mobilis is somewhat slender with the 

 end subacute, the setae rudimentary. Maxillae (fig. 2 d) with the two branches of the outer lobe extremely 

 slender. Maxillipeds (fig. 2 e) about as in Munnopsis, but the two distal joints are shorter. 



The three posterior thoracic segments immovably fused with each other and with the abdomen; 

 the feeble linear impressions between the segments show by their extreme curvature that almost half 

 of the dorsal part of fifth segment has the sixth tergite as its upper wall, while the lateral parts of 

 fifth segment are seen running far backwards when the animal is inspected from above (fig. 2 a), and 

 a similar structure is found as to seventh segment in proportion to the sixth ; fifth segment is narrow 

 at the base and not overlapping any part of the fourth. - - First pair of legs (fig. 2 g) very slender 

 and similar in both sexes, with fifth joint conspicuously longer than the sixth. Second pair of legs 

 (fig. 2 h) more than two-thirds as long again as first pair, moderately slender, distinctly thicker and 

 in proportion to the body somewhat longer in the male than in the female. Third and fourth pairs 

 nearly as in Munnopsis. Natatory legs very slender; the two distal flattened joints very narrow; fifth 

 joint without setae on the distal part of the hind margin, and the anterior margin of sixth joint naked 

 excepting towards the end. 



Abdomen very slender. -- The median lamella of the male operculum navicular (figs, 2k and 

 2 m), much compressed, somewhat broad beyond the middle and then considerably tapering to the end, 

 where each half terminates in a triangular lobe; second pair of pleopods quite independent to the base 

 as in Munnopsis; the copulatory organ has its basal part very thick (fig. 2 n) and the part beyond 

 the minute vesicle produced into an extremely long thread (/, t). Female operculum navicular, much 

 compressed with a median keel, posteriorly scarcely emarginate. Uropods short, very slender, 

 two-jointed. 



Remarks. In 1905 Tattersall established the genus Munnopsoides, took Munnopsis australis 

 Beddard as its type, and referred his new species M. Beddardi to the same genus. Now M. australis 

 Bedd. seems to be at least very closely allied to Munnopsoides eximius n. sp., so that the generic 

 characters pointed out in this species are in all probability to be found in M. australis. But as said 

 already on p. 153, M. eximius differs extremely from M. Beddardi Tatt. in the structure of second 

 pair of male pleopods, and, besides, considerably in the shape of first pair, so that I create the genus 

 Pseudomunnopsts for the reception of M. Beddardi. Another difference of probably generic value be- 

 tween P. Beddardi and Munnopsoides is found in the first pair of legs, which are very slender in 

 M. australis and M. eximius, but robust in Pseudoni. Beddardi. 



