956 NOTES ON AUSTRALIAN EARTHWORMS, 



13. PerichjEta austrina, n. sp. 



(Plate XIII, fig. 5.) 



In six specimens the number of segments varied from 110 to 128, 

 the length from 75 to 90 mm., the breadth was 5 mm., and the 

 length of the preclitellar region 12 mm. The worms of this species 

 live together with, and closely resemble P.australis (p. 361) in many 

 of their characters, but the two species are readily distinguishable. 

 The new worms are smaller, but, in regard to the shape and colour 

 of the body ; in having interrupted circles of setae, the latter being 

 more numerous in the posterior region ; in having the male pores 

 on papillae on xviii, and the oviducal pores on xiv ; in the principal 

 characters of the alimentary canal, and in the absence of caeca in 

 xxvi ; in the number, situation, and characters of the testes, of the 

 ciliated rosettes, of the ovaries, and of the oviducts ; and in the 

 general characters of the vascular system, and of the segmental 

 organs, the two species agree very closely. 



They differ in the following respects: — (1) the prostomium 

 extends further back on the buccal ring (for f or even more of its 

 width), and is marked by a median longitudinal groove which is 

 prolonged backwards so as completely to divide the buccal ring, 

 the latter also divided in the median ventral line by a distinct 

 groove ; (2) the clitellum comprises nearly the whole of xvn in 

 addition to xiv, xv, and xvi ; (3) the number of setoe is slightly 

 different, there being 16 per segment in front of the clitellum, 24 

 or sometimes 20 for the greater portion of the region behind it, 

 while in the last \ or \ inch of the body except in the last few 

 segments of it, the number may increase from 32 to 40, the setaa 

 in this region being finer, closer together, sometimes at irregular 

 intervals, and the dorsal interruption having all but disappeared. 

 But the most characteristic points of difference are (a) the presence 

 of three instead of two pairs of sperm athecse, and in the more 

 ventral position of their apertures ; (b) the presence of ventral 

 rectangular thickenings presumably of the nature of adhesive discs 

 on segments ix and x, and of copulatory or genital papillae on 

 segments xvn to xix ; and (c) the absence of a £7-shaped genital duct. 



