276 NEREIS PELAGICA. 



about sixteen, though sometimes seventeen or eighteen are present. Levinsen (1883) 

 likewise mentions that the first sixteen are unaltered. 



The fifty-seventh foot (Plate LXXI, fig. 7 g) differs little from the preceding 

 except perhaps in the narrower dorsal and more attenuate dorsal and ventral lobes, and 

 the diminished number of crenations on the under surface of the dorsal cirrus. These 

 crenations disappear before the eightieth foot, which presents a somewhat fusiform 

 dorsal cirrus and a tapering ventral cirrus. 



The eightieth foot (Plate LXXI, fig. 7 h) shows considerable modification of 

 the parts, though the plan is similar to the fifty-seventh. The dorsal cirrus is now 

 smooth. 



In a large epitokous example procured by Mr. Gray in the stomach of a salmon at 

 Berwick-on-Tweed, a curious transverse mark, simulating a pit on one side, occurred 

 behind each posterior eye. 



In certain examples from the deeper water of St. Andrews Bay the paragnathi of 

 the basal segment of the proboscis in extrusion present certain variations. Thus the 

 anterior row of large isolated points is very regular and distinct, each occupying its area, 

 whereas the smaller teeth behind are very minute and at first sight almost invisible. The 

 widening of the head and the increase in the size of the eyes are often marked. 



In a pelagic male the dorsal cirri of the first seven segments are much enlarged, the 

 filiform tip only extending from the bulbous end of the cirrus. Moreover, the ventral 

 cirri have the same shape. These curious cirri thus approached those anteriorly in 

 N. Burner llii. 



The first foot in an epitokous male more or less agrees with that in the atokous 

 form, consisting of a single lobe superiorly and another below the setigerous lobe with the 

 single spine. In this, a large specimen, the dorsal and ventral lobes are bluntly rounded 

 and short, but in the smaller forms (males) they are more elongated, though still with 

 a bluntly rounded tip. The dorsal cirrus in the large example is long and tapering 

 (Plate LXX, fig. 7) with a slight thickening of its base dorsally, extending about a third 

 of the length of the process. The dorsal and ventral lobes form short, bluntly rounded 

 cones. The intermediate setigerous lobe ends in a short bifid cone, bearing superiorly 

 bristles with long tapering tips and interiorly some with shorter tips, considerably 

 longer, however, than the ordinary types. 



In another epitokous male the changes are only evident in the twenty-third foot, 

 though a small process occurs at the base of the ventral cirrus of the twenty-second foot. 

 In this foot (twenty-third) a process appears at the base of the dorsal cirrus, and the 

 cirrus itself is clavate. The dorsal lobe is not much altered. The superior setigerous 

 lobe bears a dense tuft of the sabre-like swimming bristles and is closely connected with 

 the lobe beneath it, which has a nearly normal outline, but in addition a large translucent 

 fan-shaped process projects downward behind the inferior setigerous lobe. The latter is 

 elongated, and a dense series of swimming bristles is developing, whilst the shafts of two 

 of the stronger bristles of the original series with short tips still remain. This lobe has 

 a large foliaceous and translucent lamella projecting from its outer and upper border. 

 The ventral lobe is tongue-shaped, and the ventral cirrus has a flattened leaf-like 

 expansion on each side of its base. 



