COPEPODS OF THE WOODS HOLE REGION 603 



41. Legs 1-segmented, flattened laterally, triangular, each with an 



apical claw; caudal rami conical, partly fused at their bases; 



in acidians 9 Aplopodus Hesse, 1869 



Legs 2-segmented, retractile, not flattened, each with an apical 

 spine; caudal rami sharply pointed, not fused at their bases; 

 in ascidians 9 Adranesius Hesse, 1865 



42. Metasome nine times as long as wide, segmentation indistinct; 



first 4 pairs of legs 2-segmented, chelate; caudal rami and fifth 



legs lacking; in ascidians 9 Podolabis Hesse, 1864 



Metasome scarcely three times as long as wide, distinctly seg- 

 mented; fifth legs lacking; caudal rami present 43 



43. Urosome 3-segmented; caudal rami conical, clawhke, turned 



outward at right angles; legs with several small apical spines; 



in ascidians 9 Polyoon Hesse, 1878" 



Urosome 1-segmented; caudal rami laminate and triangular, 

 fused at their bases, the tips divergent; legs with 1 stout 

 apical claw; in ascidians 9 Pachynesthus Hesse, 1878" 



44. Three pairs of 1-segmented legs present; first antennae 7-seg- 



mented; second antennae 3-segmented, with 4 or 5 unequal 



apical setae, no claws; on annelids 9 Anomopsyllus G. O. Sars, 1921 



Only 2 pairs of 1-segmented legs present 45 



45. Second antennae 3- or 4-segmented, each with a single apical 



claw; caudal rami short, somewhat divergent and tipped 



with spines; in alcyonarians 9 Lamippe Bruzehus, 1858 



Second antennae 1-segmented, with an apical claw; caudal 

 rami half as long as entire body, conical and unarmed; 

 cuticle papillose; in alcyonarians 9 Linaresia Zulueta, 1908 



Second antennae 1-segmented, each with a single apical claw; 

 caudal rami short stumps, each with 3 fleshy papillae but 

 without setae; in alcyonarians 9 Isidicola Gravier, 1914 



46. Metasome and urosome indistinguishably fused, without seg- 



mentation; no appendages except rudiments of the first 

 antennae; dredged, 8 fathoms (see p. 621). _ 9 Jeanella T. Scott, 1904 

 Metasome and urosome distinctly separated, segmented or not 47 



47. Two pairs of antennae and 3 pairs of mouth parts present 48 



Neither antennae nor mouth parts present 49 



48. First antennae 5-segmented, setiferous; second antennae 3- 



segmented, prehensile; urosome 2-segmented; no foldings or 

 invagination of body; on annelids 9 Nereicola Keferstein, 1863 



First antennae 4-segmented, hairy; second antennae 2-seg- 

 mented, prehensile; urosome 1-segmented, invaginate into 

 metasome; body folded ventrally; in ascidians. 



9 Ooneides Chatton and Br^ment, 1915 

 19. Metasome elliptical and distinctly segmented; urosome 3-lobed, 

 not segmented; body without lateral processes; head fused 

 with thorax; on annelids c? 9 Melinnacheres M. Sars, 1870 



Metasome broadly ovate, not segmented; urosome 2-segmented; 

 head separated from thorax; latter with 4 pairs of pointed 

 lateral processes; on nudibranchs^ 9 Lomanoticola T. and A. Scott, 1895 



" Hesse claimed that the first antennae of Polyoon and Pachynesthus were biramose, both exopods and 

 endopods distinctly segmented! 



