37 '6 OLIGOCHAETA 



I 



CHAT. 



thecae from the male pores (segments 5 and 12), and by the 

 paired or unpaired glands that have been already compared to the 

 calciferous glands so universally present among earthworms. On 

 the other hand, the male ducts are confined, as in the lower 

 Oligochaeta, to two segments, upon one of which the internal, 

 upon the other the external orifice is situated, and the oviduct is 

 reduced to a simple pore, as in Naids ; but this may be merely 

 a matter of convergence by degeneration. Perhaps the most 

 remarkable genus in the family is Anachaeta, which has no 

 chaetae, but in their place a large cell projecting into the body- 

 cavity, which appears to represent the formative cell of the 

 chaeta. The integument of this genus contains true chlorophyll, 

 according to Vejdovsky. 



A singular character, found, however, also in Rhynclielmis and 

 Sutroa among the Lumbriculidae, is the opening of the sper- 

 mathecae into the alimentary canal. This was originally dis- 

 covered by Dr. Michaelsen, but has been abundantly confirmed. 



Stercuhis is a singular genus which was originally found in 

 manure, and has the peculiarity that the alimentary canal is often 

 aborted ; this degeneration seems to bear some relation to the food 

 and conditions of life. 



Fam. 3. Discodrilidae. 1 This family consists of small para- 

 sitic forms which were at one time assigned to the Hirudinea ; 

 there seems, however, to be no doubt that they are rightly 

 included in the present Order. Branchiobdella is found upon 

 the gills of the Crayfish, Astacus fluviatilis ; the American 

 Bdellodrilus upon Ca?nbarus. The chief reason for the former 

 inclusion of these worms among the leeches was due to the 

 absence of chaetae and to the presence of chitinous jaws and of 

 suckers ; apart from these structures there is nothing whatever 

 leech-like about the worms. Bdellodrilus has two pairs of testes 

 in segments 5 and 6 ; there are two pairs of sperm-ducts, all 

 opening, however, by a common " atrium " on the sixth seg- 

 ment ; on the fifth open a pair of spermathecae, likewise by a 

 common pore. The ovaries are in segment 7, and the ova escape 

 by a pair of pores apparently like the single pore of the Enchy- 

 traeidae. The entire worm consists of only eleven segments. 



Fam. 4. Phreoryctidae. 2 This family contains only two 



1 J. P. Moore, "The Anatomy of Bdellodrilus" J. Morphol x. 1895, p. 497. 



2 Beddard, Trans. Roy, Sot. Edin. xxxv. 1890, p. 629, and xxxvi. 1892, p. 1. 



