94 



Mr. F. E. Beddard on the 



spermathecse which open on to the exterior in the following 

 segment (the 13th). I am inclined to regard the diver- 

 ticulum in question as the equivalent of the second vas 

 deferens of the Lumbriculid^ ; and it may also furnish a clue 

 to the origin of spermathecae. It seems a reasonable hypo- 

 thesis to derive these organs from diverticula of the genital 

 ducts. At present, however, both these suggestions are put 

 forward only tentatively. 



This genus can be recognized as a perfectly distinct form 

 by an examination of its external characters only, which 

 is by no means always the case with the Oligoch^ta. 



The set^e are highly characteristic, and their shape can be 

 best appreciated by an inspec- 

 tion of the accompanying Fig. 2. 

 woodcut (fig. 2). The dorsal 

 rows consist each of a single 

 capilliform seta, not unlike 

 those of the Tubificidse {cf. 

 e. g. Antonin Stole " Mono- 

 graphic Ceskych Tubificidu, 

 Morfologickd, a Systeraatika 

 Studie," Abhandl. bohm. Ges. 

 Bd. vii. 1888, Taf. iv. fig. 

 13«1) ; in some of the an- 

 terior segments only was there 

 occasionally a second seta, but 

 of the same form. The ven- 

 tral rows are made up of a 

 series of paired seta3 — one 

 pair in each row. The two 

 setse of each pair are not quite 

 alike in form, and one is 

 markedly larger than the 

 other. This can hardly be 

 due to a difference in age, as 

 every segment corresponded. 

 These seta3 are not quite 

 similar to those of any other 

 genus of Oligochteta. Their 

 extremities are not bifid. I 

 am disposed to regard this 

 genus as the type of a new 

 family lying between the 

 Lumbriculidae and the Naido- 

 morpha, though its affinities to 

 both are only very general j but our knowledge of the aquatic 



Setae of Phreodrilus. 

 (I, dorsal seta ; b, c, ventral setae. 



i 



