Earthworms of the Vienna Museum. 133 



The atria are two ])airs lyiiii^" in segments xvii. and xix. 

 respectively; the anterior j)air an; much the lar^-or ; both are 

 coiled tubular glands and both are furnished with penial seta;. 

 The anterior larger atria are furnished with five of these seta?, 

 the posterior smaller pair have only two. This was only the 

 case, however, on one side of the body ; on the right side there 

 were only two to each atrium. They are curved in form and 

 show a transverse striation such as is usually found in large 

 seta} up to nearly the free tij). The free extremity of the 

 seta? is not ornamented in any way. 



There are apparently two pairs of spermatheca?. In 

 describing the external characters I have referred to the 

 external aperture of the second pair, which are considerably 

 the larger. Supposing that during copulation the worms lie 

 in opposite directions, as is the case with Lumhricus, the 

 larger pair of spermathecfB would correspond to the larger 

 ])air of atria. Whether the ditfcrence in size is a question of 

 maturity or indicates a commencing disappearance of one 

 pair of atria and of the spermathecfe corresponding to them 

 I am unable to conjecture. The larger spermatheca showed 

 a protuberance on the inner side near to its external aperture ; 

 this I suppose to be a diverticulum. Behind the second pair 

 of spermatheca? is a pair of oval glands of the same appear- 

 ance but smaller than the spermatheca. Between the two 

 glands was a sac containing one or two copulatory setse ; these 

 are smaller than the penial sette and of a somewhat different 

 form, but resemble them in being unornarnented at the tip. 

 Behind this pair of glands is another pair apparently also 

 furnished with penial set^e; but I am not certain as to this 

 point or as to whether they lie in the same segment or in the 

 next. Structures similar to these have been described in 

 other species o{ Acanthodrilus — for instance in A. Layardi* . 



There are now four or five aqnaiic Acanthodrilids known. 



EXPLANATION OF PLATE YII. 



Fig. \. Posterior extremity of Aniens heterostichon, to show tlie diver- 

 gence of the se tie. s, ventral, a', dorsal setas; m, nephridiopores ; 

 a, anus. 



Fig. 2. Genital segments of Geoscolex ma.rimus. D.V., dorsal blood- 

 vessel ; H, " heart"' connecting- dorsal with ventral blood-vessel ; 

 As, oesophagus ; Ca, ealciferous gland : V.S., sperm-sac bent 

 upon itself ; F.r?., vas deferens : A ^, atrium. The organs of the 

 left side onlv are shown. 



* F. E. Beddard, " Note on the Structure of a large Species of Earth- 

 worm from New Caledonia," P. Z. S. 1886, p. 173. 



