The ArenicolidcB oj South Africa. 5 



may attain a girth of about 70 mm., but their tail region is usually 

 less massive than that of A. loveni. The other species of Arenicola 

 are much smaller than these ; the largest known examples of A. 

 claparcdii Levinsen, A. assimilis Ehlers, and its variety affinis 

 Ashworth, are about 220 mm., and of A. ccaudata Johnston and 

 A. grubii Claparede about 250 mm. long. 



COLOUR. 



All the specimens are brown in colour ; the shade varies a little 

 in different regions, being usually slightly darker in the anterior 

 portion. 



PROSTOMIUM. (Plate I., Fig. 1.) 



The prostomium of the type specimen is beautifully preserved. 

 It consists of a large median lobe and two small lateral lobes of 

 almost uniform width (that is, not dilated anteriorly), and united 

 posteriorly in a narrow median portion the central part of which is 

 depressed slightly below the level of the lateral portions. The 

 transverse diameter of this prostomium, at its widest part, is about 

 2'2 mm. 



In three of the Saldanha examples the prostomium is well pre- 

 served. In each case it agrees in the form and proportion of its 

 parts with that of the type specimen. In the Saldanha specimen, 

 in which it is best seen, the prostomium has a transverse diameter 

 of 3 mm. of which the median lobe forms 1-8 mm. 



The nuchal organ is present and has the usual relation to the 

 prostomium. 



SEGMENTATION AND PARAPODIA. 



This species has nineteen chaetigerous segments, on each of which 

 notopodia and neuropodia are clearly seen. Each of the segments 

 from the fourth to the nineteenth inclusive is subdivided into five 

 annuli, the fourth of which the chaetigerous annulus is the 

 largest. Behind the third chsetigerous annulus there are, there- 

 fore, four smaller rings between any two successive chaetigerous 

 ones. Between the third and second chaatigerous annuli there are 

 three rings, between the second and first there are two, and in front 

 of the first chaetigerous annulus there are three rings, as stated in 

 Kinberg's diagnosis (" segmentum buccale triannulum ") and the 

 prostomium. The annulation of the anterior end is as represented 

 in Kinberg's figure and in the accompanying diagram (Text-Fig. I.). 



The difference in the sculpturing of the skin of the pre-branchial 



