COPEPODS OF THE WOODS HOLE REGION 601 



24. Head separated from thorax by a short neck; sides of metasome 



deeply incised; fifth legs laminate, three times as long as wide; 



in ascidians ? Lygephilus Hesse, 1865 



Head passing insensibly into thorax without a neck; sides of 



metasome smooth and not incised 25 



25. Fifth legs curved laminae, meeting dorsally and covering 



bases of ovisacs; second antennae flattened laminae, 1- or 

 2-segmented; in ascidians 9 Enterocola Beneden, 1860 



Fifth legs straight laminae, not meeting dorsally nor reaching 

 the ovisacs; each 3-lobed with 3 setae; second antennae 

 cylindrical; in ascidians. _ ? Haplostomella Chatton and Harant, 1924 



Fifth legs fingerform, conical, or wartlike, not meeting dorsally 26 



26. Body often unsegmented; rami of legs equal, exopods lanceo- 



late, with apical claw and outer teeth; endopods laminate, 



unarmed ; in ascidians 9 Tranestoma Wilson, 1924 



Body always segmented; endopods lanceolate, with inner teeth 

 and much longer than the laminate and unarmed exopods; 

 in ascidians ? Cryptopodus Hesse, 1865 



27. Head separated from thorax; latter fused with urosome and 



not segmented; body cavity used as an incubatory chamber; 



in ascidians 9 Scolecimorpha G. O. Sars, 1926 



Head fused with first segment; body more or less segmented, 

 with the usual dorsal brood pouch; cuticle hairy at both ends 

 of body; in ascidians 9 Brementia Chatton and Brement, 1915 



28. Exopods of first 4 pairs of legs 1-segmented, with apical claws; 



endopods circular pads, with papillae; body distinctly seg- 

 mented; in ascidians cT 9 Zanclopus Caiman, 1908 



Exopods of first 4 pairs of legs spiniform, endopods finger pro- 

 cesses, unarmed; metasome segmented, urosome fused into 

 1 segment; in ascidians 9 Lequerrea Chatton and Harant, 1924 



29. Rami of first 3 pairs of legs l-segmented, fourth and fifth pairs 



lacking; first antennae 6-segmented; second antennae 3- 



segmented, 5 setae; on annelids 9 Chelonidiformis Hesse, 1869 



Rami of first 3 pairs of legs 3-segmented, fourth pair different 30 



Rami of second, third, and fourth legs 3-segmented, first pair 



different 31 



Exopods and endopods segmented differently, some often 



lacking 32 



30. Fourth endopod 2-segmented, exopod 3-segmented; fifth legs 



reduced to spines; posterior corners of head with spines; a 



brood sack; in ascidians 9 Doroixys Kerschner, 1879 



Fourth endopod 2-segmented, exopod 1- or 3-segmented; fifth 

 legs cornuate and curved; head without spines; eggs in 2 

 external ovisacs; in ascidians 9 Blakeanus Wilson, 1921 (p. 391) 



31. Males only; rami of first legs 2-segmented; first antennae 6- 



segmented; second antennae prehensile, 2-segmented; fifth 



legs setigerous stumps; in ascidians cf Ophioseides Hesse, 1864 



Both sexes; first endopod 2-segmented, exopod 3-segmented; 

 first antennae 7-segmented; second antennae 3-segmented, 

 prehensile; fifth legs 2-segmented; in ascidians. 



d^ 9 Notopterophoroides Schellenberg, 1921 



