Description of a iSpedes of Caligus. 235 



oblique position. This may be considered an appendage to the 

 maxiUiped just described. It is similar in the two sexes. 



The second pair of maxiUipeds are rudimentary. They are 

 situated along side of the buccal mass. The basal joint is a large 

 fleshy mass, having a strong spine directed backward on its poste- 

 rior side, (fig. 4, a.) Upon this mass near its anterior part, there 

 is a very short cylindrical leg, of a single joint, which bears at its 

 apex a long slender spine, and three or four small seta. It moves 

 in every direction, and the spine is as frequently pointed inward 

 or backward, as in the manner given in the figure. 



The legs of the third pair are situated each on a fleshy base, 

 just exterior to the spine of the preceding pair. They are long 

 and slender, and composed of three joints. The basal joint is 

 rather longer than the two terminal joints of the first pair, and 

 diminishes very gradually to its apex. The second joint is one 

 third longer than the basal, and about one fourth as large, and is 

 of uniform size throughout. At its apex, below, it has a slender 

 ensiform extension, which is doubly edged with a finely pectina- 

 ted membrane, (fig. 4, b.) The terminal joint, is very similar to 

 the process just described, but is much longer. A single short 

 spine is situated on the second joint, a short distance from the ar- 

 ticulation of the terminal joint. 



The fourth pair, the last of those on the cephalic segment, is 

 very dissimilar in the two sexes. In the male (fig. 1,) it consists 

 of a very large basal joint, articulated at its extremity with a stout 

 terminal claw, which curves inward and is usually brought in con- 

 tact with a strong spine near the apex of the basal joint. The 

 breadth of the basal joint is nearly one half its length, except at its 

 insertion, where it is quite small. Between the strong spine just 

 noticed, and the apex of this joint, there is a small fleshy promin- 

 ence, and a stout spine. The terminal claw has a small seta near 

 its apex. 



In the female, (figs. 18 and 18 b,) the greatest breadth of the 

 basal joint is scarcely one fourth its length, and it is destitute of 

 the strong spine, near the apex ; in some young females we see 

 traces of it, and the leg has more bulky proportions than here 

 stated. The terminal joint is much longer and larger, and more 

 fleshy than in the male ; it has a short spine at its apex, and three 

 or four short setas. 



The remaining pairs of legs are four in number ; three pertain 

 to the anterior thoracic segment and one to the posterior. 



