no. 1404. />, ijrj siTK ' COPEPODS—CALIGIDM— WILSON. 575 



about the same length and diameter as the basal joint. At the bases 

 of the spines are small semicircular laminae f ringed with hairs like those 

 in C. rapax and several other species. The fifth legs are not visible 

 dorsally. 



Total length 5.6 mm. Length of carapace 2.3 mm.; width of cara- 

 pace 2.2 mm.; length of genital segment 1.9 mm.; length of abdomen 

 1. 1 mm. ; length of egg tubes- 2.5 mm., 50 eggs in each. 



Male. — Carapace a little more than half the entire length, longer 

 than wide, otherwise similar to that of the female (fig. 91). 



Free thorax segment bearing the same relation to the carapace as 

 in the female, but being wider than the genital segment, owing to the 

 diminution of the latter. 



(ienital segment a very narrow spindle shape, less than one-fourth 

 the width of the carapace, and three fifths as wide as long. 



It is wrinkled where it joins the free segment just as in the female, 

 but is narrowed almost none at all, for it is already much narrower 

 than the genital segment in consequence of its spindle shape. Abdo- 

 men the same length as the genital segment and two-thirds as wide, 

 made up of two joints, of which the anterior is considerably shorter 

 than the posterior and subspherical in shape. Anal laminge very large 

 and foliaceous. Appendages as in the female except that the poster- 

 it >r antenna 3 are branched, while the first maxilla? are elongated into a 

 long, slender hook, evidently used in prehension. The second maxil- 

 lipeds are enlarged and form the chief organs of prehension. The 

 fourth legs are relatively large and overlap somewhat the basal joint 

 of the abdomen. 



Total length 3.1 mm. Length of carapace 1.85 mm. ; width of cara- 

 pace 1.7 mm.; length of genital segment 0.7 mm.; width of same 

 0.13 mm. 



Color a light horn yellow, delicately pencilled with pigment spots of 

 pink and red, which are most prominent along the central axis of the 

 carapace and in the posterior lateral angles. 



(mutabilis, changeable, referring to the shape of the genital seg- 

 ment at different times.) 



This species agrees somewhat with a variety of C. gurnardi figured 

 by K rover (1863, pi. n, fig. 3, g), but the carapace is proportionally 

 shorter and broader, the lunules are larger, and the furca is much 

 more slender. 'Flic species //■/■//(//is described by Heller (1865, p. 177, 

 pi. XV, tigs. T and 8) has similar large lunules, but a much narrower 

 carapace and a very different furca. The species isonyx, Steenstrup 

 and Liit ken I L861, p. 358, pi. in, fig. 5), has very much the same pro- 

 portions, but differs markedly in structural details. 



It can he readily distinguished from other American forms by the 

 simple fact that it is the only one having the abdomen about the same 

 length as the genital segment and two-jointed. 



