674 OLIGOCHAETA 



iv/vii. The gizzard is in vii ; the intestine, which has a typhlosole, begins in xiv. 

 The dorsal vessel, contrary to what is found in all other species, is simple throughout ; 

 but the hearts are in the same segments as in other species. The two sperm-ducts 

 of each side of the body retain their distinctness until just before the external 

 opening ; in other species they join directly after their origin from the funnels. The 

 funnels are said by ROSA to be simple in structure and to pass into the walls of 

 the sperm-sac. The first pair of nephridia possibly opens into the mouth-cavity ; 

 the anterior nephridia have no caecum, which is present in those which follow ; the 

 exact number however which have no caecum is not stated. The copulatory glands 

 appear to be without setae; they are very much more numerous than in other 

 species. 



Genus CALLIDRILUS, MICHAELSEN. 



DEFINITION. Setae paired, the individual setae further apart anteriorly than 

 posteriorly. Spermathecae six pairs in XIII. Male pores open on to XVII 

 through a muscular sac. 



This genus is at present only known by a single species, unless we are to regard 

 it as synonymous with the subsequently described Bilimlm (q. v.). Our knowledge of 

 it is entirely due to MICHAELSEN (12). 



This genus agrees with Kynotus in having a terminal sac into which the sperm- 

 ducts open ; this has been described by MICHAELSEN in a later paper (10) ; the 

 description is illustrated by a figure. This sac is not muscular like that of Kynotus, 

 but consists of an irregular lobate mass of cells with very indefinite boundaries ; the 

 nuclei, however, were apparent ; a fine canal arises from this body, concerning the 

 destination of which no information is forthcoming ; it is suggested that it may be 

 the sperm-duct. 



Callidrilus has not got the accessory copulatory structures found in Kynotus ; in 

 their place are a number of superficial papillae similar to those found in Acantho- 

 drilus and other genera (see p. 145). It has, however, as have Kynotus and Microchaeta, 

 numerous spermathecae in the neighbourhood of the ovaries, occupying only one 

 segment, the thirteenth ; some of the pouches lie on one, some on the other side of 

 the septum dividing segments xiii/xiv. The testes and ovaries are quite normal in 

 position ; so are the oviducts. Other peculiarities I shall reserve for the description 

 of the species Callidrilus ucrobifer. 



