660 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



First pair of thoracic legs chelate; carpus small, triangular, and 

 closely united with the propodus, which is thickened in the male, with a 

 broad, low tubercle on the inner margin a little above the base; dactylns 

 more than half as long as the propodus, its palmary edge armed with 

 spines, of which the distal ones are the larger, and at the end with a 

 large spine ; carpus and propodus in the remaining six pairs of legs of 

 about equal length, movably articulated, and armed with acute spines 

 along their posterior edges; dactylns much less than half as long as the 

 propodus, armed with spines along the posterior margin, and biungnicu- 

 late at tip. Three proximal segments similar in all the legs, the first 

 being longest, and the third short and triangular, or quadrant-shaped. 



The first abdominal segment is furnished, in the males, with two pairs 

 of appendages, of which the outer is composed of a small oval plate, 

 with a few articulated spines along the inner border, and articulated at 

 its extremity with a larger and longer plate, which is expanded alpn* 

 its outer border, and ciliate along its exterior and distal margin. The 

 inner or upper pair of appendages consists, on each side, of a robust 

 quadrate plate, to the distal margin of which two biarticulate rami f,re 

 attached. The inner ramus has its proximal segment short, much 

 ■expanded, but not in the form of a hook, as in A. aquaficiis as figured by 

 Sars;* its terminal segment is pear-shaped, as in that species. The 

 outer ramus has its proximal segment also expanded and triangular; 

 the distal segment quadrate and ciliate externally and distally. 

 The corresponding abdominal segment, in the females, with a single 

 ■pair of plates, which are subquadrant-shaped but Jjroader than long, 

 with their inner margins straight and meeting each other on the 

 median line. Outer plates of the next pair of abdominal appendages 

 thickened, and forming an operculum covering the remaining branchial 

 plates. These opercular plates are semi-ovate, truncated at the extrem- 

 ity, straight on the inner side, and meet along the median line. They 

 are each divided into two very unequal portions by a suture, running 

 from near the end of the inner straight margin, diagonally across the 

 plate, to a point on the outer curved margin about one-third of the way 

 from the base to the apex; the distal portion is thus much the smaller. 



Posterior pleopoda, or caudal stylets, slender; proximal segment 

 somewhat larger than the fourth segment of the antennre, cylindrical, 

 as are the two rami, of which the outer is only half as long as the inner. 



Length, excluding antennae and caudal stylets, 8'"'" to 13""". 



Color above dark-fuscous, spotted, and mottled with yellowish. 



Common among Gladophora^ in 8 to 13 fathoms, ou the south side of 

 the island of Saint Ignace, also in 4 to C fathoms at the eastern end of 

 that island, and in 6 to 8 fatlioms among the Slate Islands in Lake 

 Superior; and since collected by Mr. J. W. Milner ou algx, drifted into 

 nets, 30 fathoms. Thunder Bay, Lake Huron. 



* Histoire Naturelle des CrustactSs d'Eaii Douce de Norvege, 1^ livraison, pi. x, tig. 

 6, 1867. 



