Gatty Marine Lahoratory^ St. Andrews. l.VJ 



red streak (vessel). It tinges spirit green, giving out a dark 

 green exndation like dark specimens of Cirratuhis. 



De Quatrefages thought that the buccal segment was in 

 abeyance (" L^'anneau buccal a presque entierement disparu^^)^ 

 yet not only the mouth-pai'ts, but the bases of the great 

 tentacles are close to the peristomium. The large tentacles 

 are prominent organs^ with a deep groove on their ventral 

 surface ; and as the edges of these are crenated, they in all 

 probability approach in function to those of Polydura and 

 other Spionidye. Above and behind the tentacles is a 

 branchia, and, as a rule, three others follow, each on the 

 dorsal arch of its segment, and with a diminishing distance 

 transversely between the bases. They are of moderate 

 length, and in some have a tendency to form curves and a 

 few coils. 



Behind the tentacles are indications of five segments, but 

 whether the imperfect first of these should be regarded 

 as an independent one may be an open question. The four 

 following have dorsal and ventral bristles of a simple tapering 

 kind, minutely serrated along the anterior edge. These and 

 the next are all narrow segments, and difler in this respect 

 from those which follow. The foot is represented by a 

 dorsal and a ventral setigerous papilla, with a ridge between. 

 The type of foot, however, changes at the seventh, where the 

 characteristic crotchets occur dorsally and ventrally. On 

 their first appearance these organs have a slight forward 

 curve of the shaft as far as the distal third, where a back- 

 ward curve t-akes place. The shaft shows only a slight 

 dilatation from the base upward for a short distance, re- 

 maining nearly of the same diameter to the neck, where it 

 bends backward and again forward at the tip (PL V. fig. 2 a)^ 

 The latter in certain antero-posterior views presents a median 

 rib and two lateral wing-like areas, but probably this appear- 

 ance is due to the thicker tissue in the centre and the thmner 

 and slightly expanded lateral regions. In lateral view the 

 hollow of the distal hook appears to be scooped out like an 

 old snuff-spoon, but there is no knob at the anterior base a& 

 in D. concharum. These hooks increase gradually in 

 strength though not in length in both divisions of the foot 

 posteriorly, and their number toward the tij) of the tail 

 diminishes, but they are of proportionally great size, and 

 thus in contrast with those of D. concharum. Two occur in, 

 the dorsal and three in the ventral division just in front 

 of the tail, but the number is variable. The alterations of 

 the contour of the tips of the hooks would indicate that 

 they have special functions in connexion with the tube, and 



