.128 Prof. M'lntosli's Notes from the 



the foregoing: lias the type of the thirteen wliicli constitute 

 the region, viz. is two-ringed, the middle sulcus having a 

 broad papilla on each side dorsally directed backward, and 

 bearing a tuft of bristles (PI. V. fig. 8), which have a long, 

 slightly curved shaft ending in a finely tapered tip with 

 wings. 



The hooks occupy a ventro-lateral position not far removed 

 from the dorsal arch, and thus in a ventral view they escape 

 notice. They occupy a similar position with regard to the 

 median sulcus of the segment, viz. project on a flattened 

 papilla or process behind it. Each hook (PL V. fig. 9) has 

 a slightly curved shaft tapered a little inferiorly, gradually 

 enlarging to the commencement of the wing, then narrowing 

 to the throat, from which the main fang comes off at a little 

 more than a right angle, and with two teeth on the crown 

 above. The wings are fairly broad, and are rounded distally 

 beyond the fang. 



Behind the last bristle-bundle a change in the segments 

 is inaugurated , for whilst they remain 2-ringed the dorsal 

 papilla for the bristles disappears, and a lateral groove is 

 gradually formed dorsally a little below the line of the 

 bristles, this groove being rendered more distinct by a 

 prominent papilla which marks the second ring of the 

 segment laterally, and indicates the line of hooks below it. 

 The mid-ventral line now presents a groove which continues 

 for fully an inch backward. Instead of the bristles dorsally 

 a line of hooks — indicated at first by a slight inflection of 

 the median groove of the segment — takes their place. 

 Ventrally a long band of hooks is present on each side, and 

 by-and-by meet in the middle line, so that this region of 

 the body is mainly concerned Avith movements in the tunnel 

 in the mud or sand. 



About the sixtieth armed segment the rows of hooks have 

 arranged themselves on a long pad on each side dorsally, 

 separated in the middle line by a considerable interval ; 

 whilst on the ventral surface the rows appear to meet in the 

 middle line, so that a continuous series stretches from side 

 to side, a slight inflection of the line in front and behind in 

 the centre indicating the seat of separation in front. 



Behind the foregoing region (sixtieth foot) the body in 

 the preparation undergoes considerable dilatation dorsally, 

 and the ventral line of hooks ends on each side laterally in 

 a pale elevated ridge which terminates abruptly superiorly, 

 a pale striated region occurring between it and the com- 

 mencement of the dorsal rows, which are still separated by 

 a considerable interval. They are recognized by the opaque 

 elevation in front and behind. 



