SLAYIKA AND OPHIDONAIS. 265 



mens sent me from Oxfordshire and Wiltshire, and also by- 

 Mr. Bolton of Birmingham, the well-known dealer in natural- 

 history objects. 



The body is composed of 30 to 35 segments ; the head rounded, 

 and thickly studded with sharp palpocils or tactile hairs ; the in- 

 tegument thick and somewhat opaque, and the more so on account 

 of the case, composed of organic debris, agglutinated, by the secre- 

 tion of the skin, in which it is usually enclosed. Through this case 

 protrude the setse and the peculiar papilliform appendages which 

 are characteristic of the genus. The setae of the ventral bristle- 

 bundles are long and strong, curved like the old-fashioned long \, 

 with a shoulder at the junction of the outer third with the rest of 

 the shaft, somewhat tapered off at the inner extremity, and with 

 the outer end divided into two nearly equal teeth. It is worthy 

 of remark that in these, as in many other Oligochseta, the teeth 

 point backwards in the anterior segments, and forwards in the 

 posterior ; so that the worm possesses the power of resisting trac- 

 tion at either end, and of moving freely backward or forward. In 

 the middle segments the teeth appear to be directed outward from 

 the middle line. 



The dorsal setae are long and strong, usually straight, or nearly 

 so. The first pair of bundles contain each one very long seta with 

 a short hooked one (somewhat resembling the ventral setse, but 

 with the shoulder nearer the outer extremity). There may be a 

 second capillary seta ; but if so, it is usually not more than half 

 the length of the primary one. The setse of the remaining dorsal 

 bundles are of the same length as the shorter one in the first 

 pair ; and all are usually straight, or nearly so. 



The touch-organs {SinnesliiigeV) are elevations of the integu- 

 ment from which protrude several short palpocils, which, as 

 shown in the drawing (fig. 4), are connected with special cells in 

 the epidermis. Similar cells, in connexion with tactile hairs, 

 occur in ChcBtogaster, where, after the use of weak osmic acid, I 

 have been able to trace the nerve-fibre from the inner end, 

 though without being able to make out its connexion with the 

 general nervous system. As, however, I have seen multipolar 

 ganglion-cells on the inner surface of the integument, there is 

 doubtless a connexion between them and the nerve -fibres of the 

 palpocils. 



The touch-organs are arranged in rings on all the segments, 

 rather more numerously on the first, though I have seen nothing 



