124 University of California Publications. | ZOOLOGY 
joint of inner ramus of second and third feet with eight bristles. 
Fifth foot lke the others. 
4 Abdomen with 5 segments, genital orifice on left side of 
genital segment. Number of joints in the anterior antennae 
reduced, at least by fusion of the first and second joints. Mouth 
parts often retrograded ; swimming feet usually as in the female. 
Fifth feet in some cases similar to the swimming feet, in others 
asymmetrical pairing organs (fig. 1b, ¢), 2 basals on each side, 
right foot (fig. 16) with 3-jointed outer and inner rami, the left 
(fig. le) with 3-jointed outer ramus without plumose bristles, 
inner ramus reduced or lacking. 
KEY TO THE SPECIES. 
91. Anterior antennae extend beyond end of cephalothorax for at 
least halt ts Hon ebhs (Hep) ele cnis pret sinix eieteriede w sfelole myemye |e ere 2 
1. Anterior antennae do not extend beyond end of cephalothorax, 
OT OM yet OL a Rew | OLNCA ail MOSUsts x ot orice stats seaside eno te 4 
2° BYIstles: OL LULA SyIMMeGriGal \. -yalcigis\ tant asvayetd enews ieee C. tenuicornis 
2. Furea with an elongated bristle on left side.................... 3 
3. Ventral surface of genital segment very strongly convex (fig. 5c) 
at ee EM erentecn, Sphere ae pn sietn oiiiene diet aE ee eee aed enamoche: oteete iets C. robustior 
3. Ventral surface of genital segment rather slightly convex (fig. 
GT ates cB ety cents cies a oayakal sets sats as hg cna mie oped Rela aoe LenS atatate C. gracilis 
4. Head not fused with thorax: cephalothorax with six segments 
(Gites) ee Bec ney ROR as CO Ee ea ckaIC cue C. finmarchicus 
4, Head fused with thorax: cephalothorax with five segments (fig. 
23) Reasae Puc ame Fee Tie URIs CIO teen tac teks otc eke co eee eee C. minor 
41. Anterior antennae longer than body by at least six joints.......... 
PE ey A POS TCI RYO ET rrr ok eel eS aca coe Cc. tenuicornis 
1. Anterior antennae not longer than body, or but slightly so....... 2 
2. Outer margin of terminal joint of outer ramus of second to 
fourth Leet) demi Gulate sot ones eters syeye fener stereos delet ele etslalote 3 
2. Outer margin of same smooth or feathered...............-.+---- 4 
3. Inner rami of fifth feet similar in structure.............. C. gracilis 
3. Inner ramus of left foot of fifth pair shortened and without bristles 
ea OC re TC qc. o Spe acne ett ae rae C. robustior 
4. Outer ramus of right fifth foot with plumose bristles on inner 
isck 1g? 0 i APNE pany terete etek fre or tieh er pau nr C. minor 
4. Outer ramus of right fifth foot without bristles on inner margin 
(fig. 1b); outer ramus of left foot (fig. le) less than twice as 
long as that of the right .............-2--+-20.- C. finmarchicus 
