Zoological Notes. 105 



prevents me from identifying the species with P.pagenstecheri 

 is the fact that, according to Vejdovsky (3, p. 53), there are 

 only a single pair of testes; these, however, are on another 

 page (p. 39) of the same Memoir said to fill segments 10 and 

 11 ; there is probably therefore an identical arrangement 

 with that which has been described by myself 



The different habitat of the two species is perhaps against 

 the identification. 



The second and smaller species differs from the first (1.) in 

 the form of the vas deferens funnel, wliich is more like that 

 of P. crassus, and apparently also of F. germanicus and F. 

 verrucosus ; (2.) in the complete absence of the peculiar 

 perivisceral corpuscles, which are so characteristic of these 

 worms. In P. verrucosus I could not find any difference 

 either in the structure or in the number of these corpuscles 

 in mature and in immature individuals. In the present 

 species I failed to find them either in mature or immature 

 individuals ; it may be regarded therefore as tolerably certain 

 that they do not exist. The only other species of Pachy- 

 drilus in which the absence of these corpuscles has been 

 affirmed is P. nervosus (see Michaelsen, p. 58). I am disposed 

 therefore for the present to regard this species as identical 

 with Fctcliydrilus nervosus ; it cannot well be identical with 

 any of the species described by Claparede (1). 



Michaelsen (2) was not able to state w^hether the blood 

 of this species is red as in other Fachyclrili ; in my specimens 

 the red or rather yellowish colour is quite apparent. 



List of Literature referred to. 



1. Claparede, E., Etudes Anatomiques sur les Annelides, 



etc. Mem. Soc. Phys. Geneve, t. xvi. (1862). 



2. Michaelsen, W., Die Oligochaeten von Slid-Georgien, 



Jahrb. Hamburg Wissensch. Anstalten V. (1888). 



3. Vejdovsky, F., Monographic der Enchytrseiden. Prag, 



1879. 



4. Vejdovsky, F., System nnd Morphologic der Oligo- 



chaeten. Prag, 1884. 



