168 



am hinteren Pol des Postseptale entspringend, meist sehr kurz. Sam- 

 enleiter lang. Samentaschen mit dem Darm kommunizierend, ohne 

 Divertikel." 



In the light of recent work this definition is faulty. The state- 

 ment that the spermathecse communicate with the digestive tract does 

 not always hold, since in B. modestus Eisen there is no such connec- 

 tion; and the statement that the spermathecas have no diverticula can 

 not now stand, since species have been described {B. alaska: Eisen, 

 B. saxicola Eisen, and B. citrinus Eisen) in which there are diver- 

 ticula on the ampulla. 



Eisen ('05, p. 61) modified the definition of the genus as follows: 

 ''Setze of equal length and straight. Head-pore between pro- 

 stomium and somite I, always small. Xo dorsal pores anterior to 

 clitellum. Intestine and oesophagus gradually merging into each other. 

 Dorsal vessel rises posterior to clitellum from a vascular sinus of 

 the intestine. One pair of sperm-sacs, surrounded by peritoneal mem- 

 brane, project from the testes forward. No single penial bulb, but one 

 or more isolated glandular papillae situated in the vicinity of the sper- 

 miducal pores, generally and principally ventral to the pores. Numer- 

 ous transverse muscles connect the ventral and lateral parietes sur- 

 rounding the spermiducal pores. Peptonephridia glands present or 

 absent. One kind of lymphocytes. Intestine generallv with chylus 

 cells." 



It will be noted that in Eisen's definition statements concerning 

 the sperm sacs and the structure of the penial bulb have been added. 

 It is doubtful if either of the two points made can be considered as 

 constant features of the genus. In B. gillcfteiisis n. sp. and B. indiciis 

 Stephenson sperm sacs are absent, and in certain species recently de- 

 scribed {B. nodosus Stephenson, B. dnhius Stephenson, and others) 

 no mention is made of them. Furthermore, B. gillettensis has a sin- 

 gle compact penial bulb not broken up into isolated papillae, and B. 

 nodosus is similar in this respect. It thus appears that the structure 

 of the penial bulb in this genus as described by Eisen is not a constant 

 character. 



About thirty-two species have been assigned to this genus, and of 

 this number eight have been recorded from North America and its 

 adjacent islands. Seven of the eight species were originally described 

 from this continent. The list and type localities are as follows: 

 B. modestus Eisen (Orca, Prince William Sound, Alaska), B. met- 

 lakatlcnsis Eisen (Metlakatla, Alaska), B. kincaidi Eisen (Popof Is- 

 land, Alaska), B. alaskcB Eisen (Gar forth Island, Muir Inlet, Glacier 



