ISOPODA. 45 



they overlie. The first joint is stout, a little longer than broad, the second and third 

 shorter and much narrower, together as long as the one-jointed nagellum, which 

 carries three apical sensory filaments. 



The second antennas have a very short first joint, the second not long, the fifth 

 rather longer than the third and rather shorter than the fourth, the three-jointed 

 nagellum being as long as the peduncle's third joint. The very short apical joint is 

 tipped with a curved spine. 



The upper lip appears to be rounded. The lower lip forms two broadly rounded 

 lobes. 



The mandibles are without palp, with small tridentate cutting plate and narrow 

 accessory plate, close to which is a strong but not elongate molar with finely 

 denticulate crown. 



The first maxilla? show only two plumose setae on the apex of the inner plate, and 

 nine not very elongate spines on that of the outer plate. 



The second maxillae are remarkably short, with short comparatively broad plates, 

 the outermost tipped with two long setae, the middle one with four that are not so 

 long, and the innermost with five that are shorter and more spine-like. 



The maxillipeds have the lobe of the second joint produced about to the end of the 

 fifth joint and armed on the inner margin with setae and with three or sometimes 

 only two hooks. The third joint is small, the fifth broadly oval, the sixth much 

 shorter, nearly as broad as long, the seventh almost tubercular ; the fifth and sixth 

 are' well fringed with setae on the inner margin. The epipod is cpiadrately oval in 

 the female, but in the male balloon-like, being very narrow at the base. 



The first gnathopods are closely applied to the mouth. They have the fourth joint 

 somewhat cup-like, much broader than the third, the fifth joint longer but not so 

 wide, the sixth narrower than the fifth but subequal to it in length, and both of 

 these notable for the trifid setae along the inner margin. The middle branch of the 

 setae is the longest. The narrowed apical part of the sixth joint has curved setae on 

 the outer margin. The finger is short and conical, and tipped with a spine. 



The second gnathopods display only five joints. The finger has its inner margin 

 denticulate and ends in a very small curved unguis, agreeing with the finger in the 

 third, fourth, and fifth peraeopods. The two preceding joints have the inner margin 

 denticulate or serrate. Of the four joints preceding the finger the second is not 

 longer than broad, the third is shorter than the first, and the first than the fourth. 

 Whether the first represents a coalescence of the first and second or of the second 

 and third joints, or whether the fourth may be a fusion of the true fifth and sixth 

 joints it is, perhaps, vain to speculate. 



The three hinder peraeopods are almost exactly alike, the second joint in the female 

 decidedly longer than the sixth, but scarcely so in the male. The third joint is 

 longer than the fourth and the fourth than the fifth. 



The first and second pleopods have two slender branches with long apical setae. 



