90 Mr. F. E. Bcddard on a 



diverticula perform, as tlie poucli was quite devoid of sperm. 

 I have often pointed out that, when diverticuLa are present, 

 the sperm is nearly, if not quite, invariably stored in them 

 and absent from the main pouch. The epithelium also of the 

 diverticula is commonly different in structure from that of the 

 pouch into which the diverticula open. However, there was 

 nothing of this kind to be observed in OordiodriJus ehr/nns. 

 Between the points where the diverticula open and the exte- 

 rior the spermatotheca is narrow ; but this narrower portion 

 is by no means so long' as it is in Gordiodrilus rohuifus {cf. 

 figs. 4 and 7). It is ensheathed by a very thick layer of 

 muscles, which are arranged in two directions. There is a 

 single layer of stoutish fibres which pass round the tube 

 and must act as a compressor, serving perhaps to eject the 

 sperm. This layer of muscles, as shown in the figure, is 

 not in contact with the lining epithelium of the tube. 

 Whether this is or is not due to reagents I am unable to say. 

 It suggests the possibility of a protrusion of the pouch. The 

 outer layer of muscles is tliick ; it has a longitudinal direction, 

 and in contracting would tend to protrude the pouch. Out- 

 side the two muscular layers is the peritoneal layer, which 

 lias the appearance of connective tissue and is provided 

 witl) numerous nuclei ; it is this layer alone which covers the 

 pouch distally. 



4. Gordiodrilus ditheca, sp. n. 

 (PL VII. fig. 8.) 



Among the specimens of the last species was a single indi- 

 vidual which showed an interesting difference from the others. 

 There was only a single pair of atria present, and in corre- 

 spondence with these only a single pair of spermatotheca. 

 In other respects the individual agreed absolutely with Go7-- 

 diodrilus elegans. 



The question is whether the absence of the atria of seg- 

 ment xvii. and of the spermatotheca3 of segment viii. consti- 

 tutes a specific character. It might possibly be regarded as 

 merely a variation. This case is quite analogous to that of 

 the earthworm which 1 described some years ago * under the 

 name of Neodrilus tnonocystis. That worm agreed in almost 

 every particular with Acanthodrilus dissimilis, including even 

 the remarkable alternation from segment to segment of the 

 nephridiopores. It only differed in having but one pair of 

 atria and one pair of spermatothecge. But the spermatothecaj 



* " Observations on the Structural Characters of certain new or little- 

 linown Earthworms," Proc. Roy. Soc. Edin. 1887, p. 157. 



