DESCRIPTIONS OF GENERA AND SPECIES 639 



The only remaining character of importance which serves to separate Anteus and EhinodrUus 

 IS the absence of spermathecae in the former genus. These structures can hardty have been overlooked 

 by three persons, Peekieb, Hoest, and myself, if they were really there ; and it will be observed that 

 they are absent in two unquestionably different species ; their absence in one species would have been 

 of less importance, since we know that these organs may occasionally be absent in particular species of 

 a genus where they are usually present (see p. 126). On the whole, therefore, I am inclined to retain 

 both the genera RMnodrilus and Anteus. I have already discussed (p. 634) the proper position, according 

 to my view, of the several species of 'Ajiteus' recently described by Michaelsen. 



The genus contains eight well-marked species, which there is no difficulty in 

 distinguishing. 



(i) RMnodrilus paradoxus, Peeeieb. 



R. paradoxus, Pebeiee, Nouv. Arch. Mus., 187a, p. 66. 

 Geogenia paradoxa, Vaillant, Annel^s, p. 190. 



Definition. Length, 150 mm. Male pores, XU/XX. Clitellar setae long and straight, 

 with more marked ornamentation than ordinary setae. Three pairs of calciferous glands. 

 No spermathecae (?). — Hah. Caracas. 

 This is the type species of the genus. Its anatomy has been described by 

 Peeeiek in his classical paper upon the terricolous Oligochaeta (3), to which account 

 a few details were added later (5). The additional matter chiefly relates to the 

 calciferous glands, which in the earlier paper were erroneously described as hearts 

 divisible into two chambers compared to an aui-icle and a ventricle. There are, 

 however, still lacunae in our knowledge of R. paradoxus; it is not certain, for 

 example, how many segments are occupied by the clitellum. Peeeier found only 

 three segments — the nineteenth, twentieth, and twenty-first — referable to the clitellum, 

 but, as he describes modified setae upon the seventeenth segment, it is clear that the 

 clitellum must extend at least as far forwards as to this ' segment. There appears 

 to be but one pair of testes and sperm-ducts. Peeeiek was unable to find any 

 spermathecae at all, and suggests the possibility of the worm being hermaphrodite. 

 I have, however, pointed out in the case of R. guliel'mi that the spermathecae are 

 not always to be found even in mature individuals ; and Benham was of opinion 

 (H) that the failure on the part of Peeeier to find these organs was possibly to be 

 explained by small size and by a position, as in R. ecuadoriensis, close to the ventral 

 median line. 



(2) Rhinodrilus tenkatei, Horst. 



B. tenkatei, Hoest, Notes Leyd. Mus., ix, 1887, p. loi. 

 Defl.nition. Length, 115 mm.; number of segments, 160. On segments XVII, XVIII, 



