276 



Metopa nasuta, Boeck. 



(PI 98, fig. 1). 

 Boeck, Crust, am ph. bor. & arct- p. 64. 



Body very short and compact, with firm calcareous integuments. Ce- 

 phalon about twice as long as the 1st segment of mesosome, lateral corners 

 transversely truncated at the tip. Fourth segment of mesosome much larger 

 than any of the others, and exhibiting a rounded dorsal carina: 1st segment 

 of urosome likewise carinated dorsally, the carina terminating in a curved 

 corner overlapping the succeeding segment. First pair of coxal plates, 

 as also the 3 posterior ones, extremely small. The other 3 pairs, on the 

 other hand, very large and deep; 2nd pair rather narrow in proportion to 

 its length, anterior and inferior edges forming quite an even curve, poste- 

 rior corner exhibiting a small dentiform projection; 3rd pair fully twice 

 as deep as the corresponding segment; 4th pair much larger than the 2 

 preceding pairs combined and subtriangular in form, distal edge nearly straight, 

 posterior extremity obtusely rounded. Last pair of epimeral plates of meta- 

 some somewhat produced at the lateral corners, which are distinctly angular. 

 Eyes very small, rounded. Antennae comparatively very short; the superior 

 ones but little exceeding in length V* of the body, 1st joiut of the peduncle 

 very large and thick, longer than the 2 succeeding joints combined, and 

 produced at the end anteriorly to a large hooded projection quite overlapping 

 the 2nd joint, flagellum somewhat longer than the peduncle, and composed of 

 about 8 articulations. Inferior antennae a little shorter than the superior, 

 and much more slender, the last 2 joints of the peduncle nearly equal-sized, 

 flagellum about the length of the peduncle. Anterior gnathopoda of the usual 

 feeble structure, propodos fully as long as the carpus, and nearly linear in 

 form. Posterior gnathopoda of moderate size, propodos about the length of 

 the 3 preceding joints combined, and oblong triangular in form, gradually 

 widening distally. palm rather oblique, though somewhat shorter than the 

 hind margin, from which it is defined by a distinct dentiform projection, its 

 edge coarsely serrated and nearly straight, bearing the 2 usual spinules in 

 front of the dentiform projection. Pereiopoda extremely slender and elon- 

 gated, and but sparingly setiferous, the 3 posterior pairs somewhat diminish- 

 ing in length, but otherwise of quite similar structure, the basal joint in 

 all being very narrow and linear in form. Last pair of uropoda with the 

 basal joint shorter than the other 2 combined, and armed with a single den- 

 ticle only. Telson very narrow, linguiform, considerably more than twice as 



