133 



Expedition, and are recorded by Mr. Fr. Beddard as M. gracihs, austmlis and 

 latift'ons; the 4th is described by Dr. Hansen as M. longicornis, from a specimen 

 procured during the German Plankton-Expedition. It is, however, somewhat 

 questionable, if all these species are actually referable to the present genus. Thus, 

 in the species described by Dr. Hansen, the structure of the mandibles is very 

 different from that in Munnopsis typica; and the Challenger species, to judge 

 from the not very exhaustive description given by Mr. Fr. Beddard, seem also 

 to differ very materially in several respects from the type species. 



Munnopsis typica, M. Sars. 



(PL LVII & LVIII.) 

 Munnopsis typica, M. Sars, Chr. Vid. Selsk. Porliandl. I860, p. 84. 



Specific Characters. Anterior division of body in female very broad, 

 rounded in outline, in male somewhat narrower, oval; posterior division very much 

 narrower and longer than the anterior. Cephalon deeply sunk within the 1st segment 

 of mesosome, and provided with 2 juxtaposed tubercles above at the base, frontal 

 part narrowly produced between the bases of the superior antennse, and transversely 

 truncated at the tip. The 4 anterior segments of mesosome separated above by 

 smooth, thin-skinned interspaces, and distinctly excavated trans ver sally, with both 

 the anterior and posterior edges somewhat elevated, lateral parts each with a 

 transversely oval eminence above, those of the 2 posterior segments larger than 

 those of the 2 anterior; coxal plates distinct, though very small. The 3 poste- 

 rior segments of mesosome combined scarcely more than half as long as the an- 

 terior division of the body, and defined by very oblique, arched sutures, the last 



2 each having 2 juxtaposed tubercles dorsally, lateral parts narrow, and extended 

 obliquely behind. Caudal segment considerably exceeding in length the 3 preced- 

 ing segments combined, and of narrow oblong oval form, with a single small 

 tubercle above at the base, tip bluntly produced, lateral edges gently curved and 

 perfectly smooth. Superior antenna 1 with the basal joint triangular in outline, 

 inner corner considerably produced, flagellum very slender and composed of 

 numerous short articulations carrying delicate sensory filaments. Inferior antennae 

 more than 4 times as long as the body, flagellum shorter than the peduncle. 1 st 

 pair of legs of same appearance in the two sexes, carpus slightly curved and 

 exceeding the propodos in length, dactylus short; 2nd pair considerably stronger in 

 male than in female, with the carpal joint slightly tumefied and densely armed 

 with short spines inside, dactylus elongated. The 2 succeeding pairs of legs fully 



3 times as long as the body, and terminating in a slender claw. Natatory legs 



