216 E. W. SEXTON. 



with long setae. Of the Huxley specimens the two males each have 

 five joints in the superior and five in the inferior flagella, the accessory 

 fiagellum 2-jointed, 1st joint long, narrow, and cylindrical, and the 

 apical joint almost rudimentary. The smaller of the two females has 

 five joints in both superior and inferior flagella. Two of the antennae 

 of the larger animal are broken, those remaining being the superior on 

 the left side with seven joints, and the inferior on the right side witli 

 six. Sars (30), p. 596, gives five joints for the superior and four for 

 the inferior. 



I have been able to compare the Huxley specimens with some taken 

 by Mr. Crawshay near the Eddystone. In these, the increase in the 

 number of the joints with growth is plainly shown. One young male, 

 3"75 mm. long, with the thumb just commencing to appear on tlie 

 hand of Gnath. 2, had four joints in the superior and four in the 

 inferior flagellum ; a larger specimen, 4'25 mm., with the thumb 

 further developed, had five in the superior and four in the inferior ; 

 two large fully adult males, 5"5 mm., with the bifid apex to the thumb, 

 also had five in the superior and four in the inferior. Of the females, 

 the smallest ovigerous one, 3 mm., had four in the superior, three in 

 the inferior ; other young ovigerous females, 4 mm., had four joints 

 in both superior and inferior. In the larger ones, unfortunately, the 

 antennae were more or less broken ; one had five joints in both inferior 

 flagella ; the largest, 6*5 mm. long, had six joints on the right and five 

 on the left superior, five joints on the left inferior ; another had six 

 joints on the right superior, four in the right and three in the left 

 inferior. 



There are two forms of antennae in both sexes in falcata. In the 

 one form the whole of the inferior antenna is swollen, and all the 

 proximal joints of the flagellum coalesced, so that only three joints 

 can be traced, the long, swollen, coalesced 1st joint, a small stout 

 joint, and a rudimentary terminal one; the accessory flagellum is 

 1-jointed and swollen. Dense fascicles of plumose setae are developed 

 on the long joint of the flagellum and on the distal portion of the last 

 joint of the peduncle. In the other form the inferior antenna is 

 more slender ; the joints of the flagellum are distinct five or six in 

 number, the number frequently different on one side from the other ; 

 no plumose setae are developed, but the curved sensory spines are 

 stronger and more numerous ; the accessory flagellum is 2-jointed 

 and cylindrical. This form is certainly near pusilla, but can be 

 easily distinguished from it ; it is much more heavily built ; the last 

 joint of the peduncle lacks the fringe of long setae, being only 

 sparsely setose ; the joints of the flagellum are short and thick ; and 



