NERINE CIRRATITLUS. 151 



De St. Joseph (1894) mentions that the bifid crotchets occur between the thirty-third and 

 the forty-fifth foot according to the size of the specimen. Long cilia clothe the inner edge 

 of the branchia. At the fiftieth foot the branchia is subulate, the lamella of the upper 

 division is hatchet-shaped, with the lanceolate point dorsal. The dorsal bristles are much 

 more slender and elongate, yet form two series as before. The narrow inferior lobe now 

 has a free process superiorly, whilst a depressed straight area beneath gives origin to four 

 winged hooks followed by a bluntly- conical termination of the lamella ventrally. The 

 hooks (Plate CV, figs. 1 c and 1 d) have toward the end of the shaft a bold upward curve, 

 then the diminished tip bends backward and ends in a small blunt fang with a spike on 

 the crown inferiorly (in the ordinary position in situ). A well-marked wing guards each 

 side of the tip, and a fibre on each side of the throat forms a thickened border to the distal 

 end of the wings. When viewed antero-posteriorly the tips of the wings thus leave the 

 crown free (Plate CV, fig. 1 b). 



Mesnil gives the numbers of these hooks in the various regions and their variations, 

 as well as the proportions of the anterior region without them at several stages. A slender 

 tapering bristle or two occur above and below the hooks. 



At the seventieth foot bristles still occupy the upper division, so that the southern 

 forms from which Mesnil drew up his description differ considerably from the northern 

 in this respect. The winged hooks have receded in the northern. 



At the ninetieth foot (Plate XC VII, fig. 2 b) the branchia has considerably diminished, 

 but the hatchet-shaped lamella of the superior lobe is even more prominent than at the 

 fiftieth. Moreover, only two of the long bristles remain superiorly, the rest of the area 

 being occupied by four winged hooks. The inferior lamella of the lower division, which 

 is separated by a deep notch, has an abbreviated upper process, and its vertical diameter 

 is shortened. The setigerous ridge beneath, on the other hand, has increased in length 

 and is more prominent, bearing a range of seven winged hooks and a bristle or two above 

 and below. The ventral enlargement or papilla beneath is similar to that at the fiftieth 

 foot. The whole outline of the foot characteristically differs from that of N. folio sa. 



The foregoing type of foot is little altered in the posterior segments which show 

 (Plate XCVII, fig. 2 c) dorsally a small branchia, and a separate hatchet-shaped lamella 

 lying, as usual in the species, behind the bristles which consist of three or four winged 

 hooks with shafts of great strength and more finely tapered tips than in front, and 

 often so worn that it is difficult to see their exact structure. One or two long winged 

 bristles are likewise present. A large gap, which is narrowed in lateral view by the 

 process of the inferior lamella, separates the foregoing from the inferior division. The 

 inferior lamella is short and narrow, and is followed by the web-like projecting setigerous 

 process or edge, bearing six or seven winged hooks of similar structure to the foregoing 

 and an upper and lower bristle or two, smaller and more finely tapered than superiorly, the 

 last process being the conical papilla, which probably is the homologue of a ventral cirrus. 

 Considerable differences exist in regard to the development of the lamellae of the feet, the 

 finest examples having been met with on Southport sands. 



In an example from St. Andrews the tail had been reproduced and formed a smaller 

 continuation of the region in front, all the processes, bristles, and hooks being present in 

 their normal condition. Moreover, ova, with the characteristic capsule and apparently ripe, 



