Galhj Marine Luhoratory^ St. Andrtws. q 



sim])le branches. The liooks approach those of A. cirrata, 

 hut have different curves, with two teeth above the main 

 fang. 



Another British species, Amphitr'tte affinis, Malmgren, the 

 fourth form, has l)een found on various parts of the coast, 

 and will be alluded to more particularly under the forms 

 dredged by the ' Porcupine.' 



Amphitrite gracilis, Grube (P/njse/ia scyUa (Sav.), De 

 Quatrefages), the fifth form, is ehiefiy a southern type which 

 also extends to Ireland. The dorsal cephalic collar forms a 

 small crenated rim posteriorly, and passes downward at each 

 side to join the lower edge of the supra-oral arch. The ten- 

 tacles which take origin from it are numerous and have the 

 typical grooved structure. They are of a pale cream-colour 

 and partly translucent. Its front edge terminates in a 

 prominent spout-shaped arch over the mouth, the sides 

 inferioily sloping obliqiiely to their attachment. The lower 

 lip is formed by a transverse fold, and within it is a small 

 tongue-like fold or eminence. No eyes are visible in the 

 preparation behind the cephalic collar. 



The body bas a hundred and twenty to a hundred and 

 forty-six segments, and is characterized by its great propor- 

 tional length, ai.d slenderness posteriorly, as well as by its 

 pale cream-colour here and there enlivened by the blood- 

 vessels and the brownish-red specks posteriorly. The 

 enlarged anterior end has further a close series of transverse 

 ridges, which have a minutely tessellated appearance from 

 isolated glandular masses ai-ranged transversely. These 

 glands have, besides the granules, clear refracting cells and 

 globules. The separation of the longitudinal dorsal muscular 

 fibres in this region also increases the tessellated aspect. 

 Beliind the bristled region the body gradually narroAvs and 

 ends in a slender tail with a terminal anus surrounded 

 by marginal papillae. The dorsal surface is convex, the 

 ventral flattened anteriorly and grooved posteriorly. The 

 glandular shields or plates in front are about twelve in 

 number, with a few (three or four) additional small median 

 processes. Behind the region of tlie shields is a median 

 groo\e with a prominent ridge on each side. At first lateral, 

 these riiiges gradually pass to the mid-ventral line, forming 

 posteriorly a raised belt with a median fissure, then widen a 

 little toward the tail, where the papillae for the hooks occur 

 in the line of each moniliform ridge, and gradually diminish 

 as the tip is reached. Whilst the seginents in front have 



