Ko. 20G3. NORTH AMERICAN PARASITIC C0PEP0D8— WILSON. 699 



two-jointed; first maxillae tripartite, palp with one or two setae; 

 second maxillae separate to the tips where they are jointed to an 

 ordinary buUa; sometimes fused; maxillipeds with a stout basal joint 

 and a long terminal claw. 



Generic cJmracters of male. — -Cephalothorax inclined more or less to 

 the trunk, from which it is separated by a well-defined constriction 

 and often by a short neck; head covered by a dorsal carapace which 

 varies considerably in size; trunk straight, spindle-shaped, and much 

 narrower than the cephalothorax; small anal laminae sometimes 

 parallel with the trunk axis, sometimes at right angles to it; often 

 with a large unpaired (genital) process between the second maxillae. 

 First antennae three-jointed, about the same length as the second 

 pair; the latter biramose, both rami one-jointed, the exopod (ventral) 

 sometimes with two joints; first maxillae three or four partite; second 

 maxillae and maxiUipeds close together and about the same size, 

 both provided with stout curved claws. 



Type. — Bracliiella thynni Cuvier. 



(Brachiella, ^pa^cajv, arm, with diminutive ending.) 



Remarks. — -This genus, like Clavella, has received many species 

 which ought never to have been assigned to it. For a long time the 

 distinction between the two genera consisted simply in the separa- 

 tion or fusion of the second maxillae. If they were fused the species 

 was placed in the genus Clavella; if they were separate it w^as referred 

 to the genus Brachiella, irrespective of its other morphological pecu- 

 Uarities. Consequently, we find here also many species w^hich must 

 be transferred to other genera, or for which new genera must be 

 created. The list which follows includes such species. There is 

 rather more dissimilarity amongst the males than in the other genera 

 but they agree very well in all essential characters. Probably w^hen 

 the species, and especially the males, become better known it will be 

 necessary to separate some more of them and establish other new 

 genera. Even the data already known with reference to such species 

 as concava and lophii make it practically certain that they must 

 eventually be placed elsewhere. But vmtil we can get the necessary 

 data it is better to keep them here where they w^ere originally placed. 



Synonyms. — Bracliiella anserina Wilson, 1908, p. 467, differs in so 

 many and so important particulars from the Brachiella here estab- 

 lished that it has been made the type of a new genus, Prohrachiella 

 (see p. 716). 



Brachiella antarctica Quidor, 1906, p. 30, pi. 3, figs. 45 to 48, has 

 no posterior processes, the exopod of the second antennae is unseg- 

 mented, the second maxillae are entirely separate, and the male 

 differs so much from Brachiella that it has been made the type of a 

 new genus, Euhrachiella (see p. 716). 



