MUSEUM OF COMPARATIVE ZOOLOGY. 25 



carapax along the margins of the sinus is in close contact with the ophthalmic 

 lobe. From the lower portion of each ophthalmic lobe there is an elongated 

 cylindrical and somewhat conical, but obtuse and pointed protuberance, of 

 which the base rests in a transverse groove in the base of the antenna, while the 

 terminal portion extends well across the open ventral side of the orbital sinus. 

 Upon the obtuse extremity of this protuberance there is a nearly circular area 

 similar to the cornea-like area at the posterior extremity of the dorsal pail of 

 the lobe. 



The peduncles of the antennulae are very stout, being stouter even than the 

 peduncles of the antennae. The basal portion of the proximal segment is longer 

 than the two distal segments, is armed on the distal portion of the outer margin 

 with two spiniform teeth, and the inner side is broadly expanded and prolonged 

 into an acute scalelike appendage upturned and densely ciliated along the 

 inner margin, and extending considerably beyond the distal segment and 

 nearly as far as the tip of the antennal scale. The second and third segments 

 are subcylindrical, and, as seen from above, are each about as broad as long, the 

 second being somewhat larger than the third. The inner or major flagelluni 

 is about as long as the carapax. The minor flagellum is about as long as the 

 peduncle of the antenna, about half as thick as the base of the major flagellum, 

 of nearly uniform thickness for three fourths its length, then tapers rapidly to a 

 very slender tip, and is thickly ciliated along the inner margin distally. 



The first three segments of the peduncle of the antenna are very short, the 

 three together being scarcely longer than the fifth segment. The first segment 

 is loosely articulated with the sternum of the antennal segment, so as to be 

 freely movable upon it ; it is very short upon the outside, but expands some- 

 what on the inner side, which terminates distally in a thin tubular process 

 arising from the oral side of the segment and directed upward to a level with 

 the dorsal side, so that, in the ordinary position of the appendages, its orifice is 

 closed by contact with the first segment of the peduncle of the antennula. 

 This tubular process readily admits a large bristle, which can be pushed 

 through it round into the cavity of the segment itself. It undoubtedly con- 

 tains the canal of the green gland. The second segment is small, closely united 

 with the third, and bears upon its outer side a slender scale, which reaches 

 nearly to the tip of the peduncle, is about five times as long as broad, and 

 thickly cUiated along both edges. The third segment, as seen from below, is 

 almost wholly internal to the second, and is armed on the distal part of the 

 inner margin with a small spiniform tubercle. The fourth and fifth segments 

 are subcylindrical, the fourth is slightly longer than the fifth, and both are 

 ciliated each side. The flagellum is about as thick at base and nearly as long 

 as the major flagellum of the antennula. 



The buccal opening is nearly square. The branchiostergites extend forward 

 quite over the sternum of the antennary somite, and their anterior extremities 

 are applied to the basal segments of the antennae, which, however, are freely 

 movable upon the antennary somite. The epistome is short, not extending at 

 all in front of the bases of the antennae, is nearly on a level with the dorsal 



