Gaily Marine Laboratory^ St, Andrews. 159 



differ considerably from the northern. The diminution of 

 the branchia goes on [josteriorly with the separation of the 

 lamella behind the bristles. Mesnil includt'S under this 

 form Malacoceros hnyirostris of De Quatrefuges, Nerine 

 agilis, Verrill, and Nerine heteropoda, Webster. 



The third species is Scolecolepis vulgaris, Johnston, which 

 lias a truncate head with a frontal tentacle at each side, 

 the anterior border forming the base of a triangle, the apex 

 of which goes to an adherent occipital tentacle. The long 

 palpi are pale, marked externally by whitish bars with the 

 zigzag blood-vessels. The eyes as a rule are absent in the 

 preparations. The body is 3-4 inches long, slightly narrowed 

 in front, and tapering posteriorly to the vent, which has 8 

 cirri (De St. Joseph gives 20-39 and Mesnil 16). The first 

 foot carries a distinct though small branchia. The bristles 

 of the upper division form a fan and are in two sections, the 

 dorsal much longer, more slender and more finely tapered, 

 and an inferior group of shorter bristles also with finely 

 tapered tips. The bristles of the fan-like ventral row are 

 similar in structure, but shorter. All lie in front of the 

 lamellse. At the 10th foot the inferior lamella is vertically 

 elongated, its upper edge embracing the branchia, whilst 

 its inferior forms a rounded lobe ventrally. The upper 

 group of golden bristles still point dorsally, but they 

 are shorter. The long lower bristle-row is curved back- 

 ward. The lamella of the inferior division is short and 

 hatchet-shaped. Beneath the foregoing is a small lamella, 

 probably homole.gous with the papilla present in Nerine. 

 No noteworthy change occurs in the 25th foot, except the 

 increase of the ventral lamella, and the same may be said as 

 far as the 50th. About the 50th, however, the elongation 

 of the ventral lamella is conspicuous, and a series of long, 

 winged hooks appear in this division. These have stout 

 curved shafts, a strong and sharp main fang, and two well- 

 marked spikes on the crown. Short bristles accompany the 

 hooks, and about three are prominent ventrally. De St. 

 Joseph found that the hooks appeared between tiie 30th and 

 52nd, whilst Mesnil gives from the 35th to the 37th. Except 

 that a diminution in the general size of the feet occurs, the 

 arrangement is similar at the 100th foot, but the dorsal 

 bristles are considerably longer and more slender. The 

 branchia remains fairly large, and the ventral hooks retain 

 the same type as in front and are accompanied by the short 

 bristles. In life the lamellae of the feet as well as the 

 branchiae, which meet those of the opposite side in front, 



