1892.] SPECIES OF EARTHWORMS, 705 



genus is so far degenerated that it possesses no gizzard, not even the 

 faintest vestige of one ; the nephridia, which in other Geosco- 

 lecidse have a large terminal end sac, very often with a capacious 

 caecum attached, are totally without anything of the kind. Another 

 indication of a low position among the terricolous Oligochseta is 

 perhaps the opening of the sperm-ducts upon the xviith segment ; 

 we find that this segment is the one which bears the pores in question 

 in the genus Ocnerodrilus and also in Microdrilus and Microscolex. 

 It is a coincidence, though probably no more, that there is but one 

 pair of calciferous glands and that these are in the ninth segment ; in 

 three low forms of terrestrial Oligochseta we meet with exactly the 

 same condition of the calciferous glands, viz., in Ocnerodrilus ', Gor- 

 diodrilus ", and in the Acanthodrilid Kerria.^ As, however, there are 

 Geoscolecids (such as Microchceta) in which the calciferous glands are 

 similarly reduced to one pair, but which are evidently not degenerate 

 forms, too much stress cannot be prudently laid upon the point of 

 similarity to the three genera aforementioned. 



Rosa ^ and I ' have independently pointed out that the family 

 Geoscolecidae can be most conveniently divided into two subfamilies, 

 confined respectively (with the exception only of Pontoscolex, which 

 is cosmopolitan) to the Old and to the New World ; I need not 

 again go into the matter here, as the reasons which led me to this 

 conclusion have been fully given in the paper quoted below. The 

 present genus interferes with the symmetry of this proposed 

 arrangement ; it evidently belongs in structure to the New World 

 section of the family, but lives in the Old World. The spermato- 

 thecae lie in front of the testes and the other reproductive organs, 

 and there are no copulatory papillae. 



The genus Ilyogenia agrees with no other genus in every point : 

 the form and position of the sperm-sacs are unique in the family ; 

 the ventral position of the nephridiopores is characteristic of the 

 genus Geoscolex, with which, however, Ilyogenia has no other marked 

 points of resemblance. It comes nearest, perhaps, to Anteus and 

 Bhinodrilvs ; but differs from both of these genera in a number of 

 small differences, which are, in my opinion, collectively at least, of 

 sufficient importance to justify its distinction by a separate generic 

 name. 



YII. EXPLANATION OF PLATES XLV. & XLVI. 



Fig. 1. Part of an egg-sac of Moniligaster bahamensis, showing ripe ova. 



2. Spei'matotheca o{ Moniligaster bahamensis: a, transverse section. 



3. Ventral view of anterior segments of same ; the segments are numbered. 



4. Male genital apparatus of the same worm ; the figure is reconstructed 



from a series of sections. 



^ " On the Anatomy of Ocnerodrilus," Tr. Eoy. Soc. Edinb. vol. xxxvi. no. 21. 

 2 " On a new Genus of Oligochseta, &c.," Ann. & Mag. Nat. Hist., July 1892. 

 ^ P.Z.S. 1892, p. 3.35. 



^ Kynotiis miclMelscnii, n. sp. " Contributo alia morfologia dei Geoscolecidi," 

 Boll. Mus. Zool. Tol. vii. no. 119. 

 ' Q. J. M. S. vol. sxxiv. p. 258. 



