271 



posterior extremity broadly rounded off. Last pair of epimeral plates of 

 metasome somewhat produced at the lateral corners. Eyes of moderate 

 size, rounded, pigment bright red. Antennae rather slender, the superior ones 

 exceeding half the length of the body, 1st joint of the peduncle longer than 

 the cephalon, and about equalling the length of the 2 succeeding joints 

 combined, flagellum half as long again as the peduncle, and composed of 

 about 14 articulations. Inferior antennae scarcely shorter than the superior, 

 the 2 outer joints of the peduncle nearly equal-sized, flagellum exceeding 

 half the length of the pedxincle. Anterior gnathopoda of somewhat unusual form, 

 basal joint rather broad and lamellar, meral joint forming inferiorly a broadly - 

 rounded setiferous lobe, carpus very narrow and elongated, somewhat 

 tapering distally, and having a single row of simple bristles along the 

 inferior edge, propodos about half the length of the carpus, and still narrower, 

 nearly linear, and without any distinctly-defined palm, dactylus very 

 short, and finely ciliated on the inner edge. Posterior gnathopoda extremely 

 strong and powerful, meral joint with a similar ascending lamella inside as 

 in M. pollexiana, propodos very large and broad, nearly quadrate in form, 

 though gradually expanded distally, palm somewhat oblique, and defined 

 below by a rather large acuminate projection, its edge slightly convex and 

 coarsely serrated in its anterior part. First pair of pereiopoda rather 

 slender, the succeeding pairs very powerfully developed, with the meral joint 

 greatly produced at the end, and the dactylus strong and minutely serrated 

 on the inner edge; last pair with the basal joint very broad, and rounded 

 quadrangular in form, meral process exceedingly large and curved, reaching 

 even considerably beyond the carpal joint. Last pair of uropoda comparatively 

 short, basal joint but little longer than the succeeding joint., and armed 

 with a single denticle only, terminal joint short. Telson nearly twice as 

 long as it is broad, and armed with 2 pairs of strong dorsal denticles, tip 

 obtusely pointed. Body whitish pellucid, with a few scattered orange-coloured 

 patches. Length of adult female 6 mm. 



Eemarks. I at first believed this form to be the M. clypeata of 

 Kroyer, owing to the somewhat similar structure of the gnathopoda. Having 

 however, recently, through the kindness of Dr. Hansen, had an opportunity 

 of examining the type specimens of Kroyer's species, I find both forms to 

 be evidently distinct. The present species is easily distinguished from the 

 said arctic form, by the antennae being equal-sized, whereas in M. clypeata 

 the superior ones are much the larger, and by the very different form of the 

 4th pair of coxal plates, as also by the much greater length of the meral 

 process of the posterior pairs of pereiopoda. 



Occurrence. I have met with this form in 2 different places off the 



