Gatty Marine Labovatori/, St. xindrews. 87 



projection. Viewed from the front the pigmented peri- 

 stoinial scf^ment terminates dorsal ly ratlier abruptly, the 

 pale cephalic keel pas-.ing downward and forward from this 

 and being lost on the symmetrically cxj)anded snout on each 

 side. The nuchal grooves occu|)y the sides of the ridge and 

 curve outward at their anterior ends, and the madder-brown 

 pigment in its symmetrical disposition often mimics an eye 

 on each side. The minute eye-specks, however, are situated 

 in a row on each side of the anterior border, between the tip 

 of the nuchal groove and the ventral edge. The fusion of 

 the [)ro- and pcristomial segments is close, and both would 

 seem to take part in tlie formation of the anterior process, 

 for the symmetrical furrows from the mouth occur on its 

 under surface. The mouth forms a transverse furrow poste- 

 riorly, whilst in front a median and two lateral furrows pass 

 forward to the snout. In examples in which the head has 

 been recently regenerated the parts are pale, the anterior 

 process or prow is shorter and has a median dimple. 



In contrast with the foregoing the snout in N. lumbricalis 

 is less produced anteriorly, a condition very evident in a 

 lateral view (PI. II. fig. 8). Moreover, antero-posteriorly 

 N. lumbricalis has a more rounded and less elevated crown, 

 whereas in A'^. maculata the crown is higher and narrower. 

 There is no specialization of pigment in separate touches as 

 in N. maculata, though the dorsal half is reddish brown and 

 the lower whitish. The nuchal grooves in N. lumbricalis 

 have a similar trend to those of N. maculata, curving gently 

 outward and separated by a flattened ridge. The snout in 

 the large Canadian iVicomrtc^e (?) (PI. II. fig. 4) diverges still 

 mere, for behind the median ridge is a deep fold of the 

 segment, the ridge itself commencing by a rather broader 

 base, aiKl, slightly narrowing, slopes downward and forward 

 to within a short distance of the anterior edge. In lateral 

 view the middle is convex. The nuchal groove closely 

 follows the somewhat narrow ridge, and thus they converge, 

 since the ridge itself is narrower in front. The groove turns 

 sharply outward on each side, making a small angle with the 

 main furrow, and thus ditters from either iV. lumbricalis from 

 Xorthern Europe or A"", maculata from Britain, in both of 

 which the curve is bold and rounded. 



Immediately behind the mouth is a transverse furrow, 

 indicating the anterior border of a narrow segment devoid of 

 bristles. It is marked by a distinct band of pigment oa the 

 dorsum, an interval separating it from that at the anterior 

 border of the pcristomial segment. The next three segments 

 are each distinguished by having dorsally a tuft of bristles 



