No. 1580. 



NE W SPECIES OF CA LTGIX. E— WTLSOX. 599 



The ovaries and musculature of the carapace are pecuhar, as is 

 shown in fig. 25. The ovaries (o) are narrow and semilunar, the 

 convex sides facing each other and almost touching at the mid line; 

 they are somewhat narrower at the center and enlarged at either 

 end, their posterior third lying within the thoracic area. The muscles 

 of the carapace, instead of being narrow and separate, as in most 

 species, are fused into broad sheets. 



This fusion necessarily modifies the direction in some instances; for 

 the fused sheet can extend in but a single direction, while the sep- 

 arate muscles nearly always diverge or may even be curved. 



This is particularly true in the thoracic area. In the present 

 species we find but four of these muscle sheets on either side, very 

 simply arranged, in place of the complicated pattern assumed by the 

 numerous (twelve or more) individual muscles in Caligus curtus^ and 

 allied species. 



The muscles which run from the thoracic area back into the free 

 and genital segments, as well as those in the two latter segments, are 

 of the usual pattern. 



Total length, 4.4 mm.; carapace, 2.35 mm.; genital segment, 

 1.1 mm.; width of carapace, 1.7 mm.: width of genital segment, 

 1 mm. 



Color, a bright orange yellow, thickly penciled above and below 

 with lines and spots of a brilliant reddish-brown or rust color. 



In some specimens the color is confined to separate spots without 

 any penciling. By transmitted light this is the most highly-colored 

 Caligus thus far described, since a wash of the rust-colored pigment 

 fills the tissues of the carapace in the innnediate vicinity of the spots 

 much as though the color had "run." This bright color, wliicli 

 appears upon the ventral surface and the appendages as well as 

 upon the dorsal surface, is alone enough to differentiate the species. 



(rufus, rust colored). 



CTialimus. — Carapace elliptical, one-fifth longer than wide; second 

 and third thorax segments not yet fused with the head, but free, 

 and, with the fourth segment, diminishing regularly in size. 



Eyes large and of a deep brown color with prominent reddish 

 lenses; situated about in the center of the carapace. 



Genital segment and abdomen still united and comparatively short; 

 anal lamina^ large, and each of them armed with six seta?. First 

 antenna^ fully developed ; second pair with a weak and nearly straight 

 terminal claw. Mouth parts like those of the adult in miniature; 

 mouth tube already very long and narrow. 



Swimming legs rudimentary, the first and second pairs better devel- 

 oped than the third and fourth. First two pairs biramose, the rami 

 simple and armed with nonplumose setae. 



"See Proc. U. S. Nat. Mas., XXVIII, p. 51«, fig. 24. 



