618 BULLETIN 159, UNITED STATES NATIONAL MUSEUM 



38. Second maxillae flat muscle bands, joined at tips, without a 



bulla; abdomen unsegmented, with caudal rami; no posterior 



processes; gills of fishes 9 Naobranchia Hesse, 1863 



Second maxillae short and completely fused, often only the bulla 



visible; a genital process, but no abdomen or caudal rami 39 



Second maxillae long and separate except at the bulla; a genital 



and 0-8 posterior processes; no abdomen or caudal rami 42 



39. Neck usually in line with second maxillae, the two continuous 



and attached to anterior end of trunk 40 



Neck usually at an angle with second maxillae, the former 



attached to side of trunk, the latter to its anterior end 41 



40. Second antennae uniramose; first antennae 3-segmented; head 



often longer than trunk; a genital but no posterior processes; 



gills and fins of fishes 9 Clavella Oken, 1815 (p. 513) 



Second antennae biramose; first antennae often 4-segmented; 

 head shorter and stouter; posterior processes usually present; 

 mouth and fins of fish 9 Clavellopsis Wilson, 1915 



41. Second antennae turned across frontal margin; first maxillae 



tripartite; first antennae setose; head reflexed dorsally; gills 



of fishes 9 Clavellodes Wilson, 1915 (p. 516) 



Second antennae turned forward; first antennae spinose; first 

 maxillae bipartite usually; head wormlike, not reflexed; gills 

 of fishes 9 Clavellisa Wilson, 1915 (p. 517) 



42. No genital or posterior processes; no carapace; exopod of 



second antenna 1-segmented; second maxillae not fused at tip; 



usually no bulla; gills of fishes 9 Eubrachiella Wilson, 1915 



A genital, and 2 to 4 posterior, processes; a carapace; exopod 



of second antenna 2-segmented; maxillae fused with a bulla 43 



No genital, but 6 to 8 posterior, processes; head flexed forward 



and not backward 44 



43. First maxillae usually bipartite, palp with a single spine; 



second maxillae dactylose at tips, or with a clavate bulla; 



gills of fishes 9 Parabrachiella Wilson, 1915 (p. 519) 



First maxillae usually tripartite, palp with 2 spines; second 

 maxillae never dactylose, but with the usual button bulla; 

 gills of fishes 9 Erachiella Cuvier, 1830 (p. 520) 



44. No carapace; first antennae 4-segmented; first maxillae bi- 



partite, palp with 2 stout spines; second maxillae separate 



to tips; gills of fishes 9 Epibrachiella Wilson, 1915 



A distinct carapace; first antennae 3-segmented; first maxillae 

 tripartite, no palp; second maxillae completely fused; gills of 

 fishes 9 Probrachiella Wilson, 1915 



45. Anterior and posterior portions of body in same line or curve, 



neither bent at an angle nor folded upon itself 46 



Anterior and posterior portions of body at more or less of an 

 angle, sometimes completely folded together and fused 55 



46. Head separated from trunk, which is often segmented 47 



Head completely fused with trunk, which is never segmented 54 



47. Trunk showing definite segmentation 48 



Trunk without any traces of segmentation 51 



48. Trunk much longer than head and neck 49 



Trunk much shorter than head and neck 50 



