DESCRIPTIONS OF GENERA AND SPECIES 661 



which are long and thin like those of the other species, often absent in specimens 

 with a fully developed clitellum. In other characters the present species appears to 

 agree with P. corethrurus. 



Genus Uhobenus, Bbnham. 



Syn. Anteus, Michaelsen (in part.), 



Dbpinitioit. Prostomium present. Clitellum, XIV (X'V)-XXIV (XXV). Setae 

 paired, ornamented only on clitellum and some adjacent segments. A pair 

 of caeca like those of Perichaeta present in segment XXVI. Sperm-sacs two 

 pairs in XII -XIV (XVI). Tliree pairs of spermathecae in VII-IX. 



We are at present acquainted with three species of this genus. It was originally 

 described by Benham (3), and recently Michaelsen (10) and Ude (4) have added 

 a second and a third species, which, however, were referred to the genus Anteus. 

 I have already expressed the opinion that these two genera are quite distinct. 



The most noteworthy character of this genus — one which serves to remove it from 

 any other Geoscolicid — is the existence of two caeca apparently precisely similar to 

 those of Perichaeta. These caeca also, it wiU be observed, occupy the same segment 

 that their homologues do in Perichaeta, which adds, of course, to the similarity. 

 The gizzai'd is, according to Benham, in segment viii ; Michaelsen, on the other hand, 

 places it in segments ix, x. It is possible that this apparent difference is merely 

 brought about by the pushing back of the septa. In Urobenus hrasiliensis there 

 are calciferous glands ; in the second species these glands are not described, but it 

 is stated that the alimentary canal resembles that of the former. 



Urobenus resembles Perichaeta in having the caeca upon the intestine ; it resembles 

 quite another genus — viz. Pontoscolex — in having a series of pyriform sacs in the 

 posterior segments of the body. These sacs, however, are not as they are in Pontoscolex 

 diverticula of the nephridia, but are independent structures opening separately on to 

 the exterior. The existence of these pyriform vesicles is another reason for regarding 

 this genus as distinct from Anteus, though it is not stated by Michaelsen whether 

 they are or are not present in U. papillata. 



(i) Urobenus brasiliensis, Benham. 

 U. tarasUiensis, Benham, Q. J. M. S., vol. xxvii, 1887, p. 83. 

 Definition. Length, 1^0 mm.; diameter, ^in.; number of segments, 9a. Setae of clitellum 



