106 AMPHITRITE CIRRATA. 



yet the tubes of the common Thelepus cincinnatus are likewise more or less spiral in certain 

 circumstances. 



The abundance of the Terebellids on the beach at St. Peter Port, Guernsey, is a 

 notable feature, and they are common in fissures of the gneiss rocks, especially from the 

 Battery to St. Sampson's. 



The classification of the Terebellidae, including the condition of the nephridia, is not 

 free from uncertainty, since the presence or absence of branchiae, their form and number, 

 the number of segments furnished with conspicuous setigerous processes, the form of the 

 hooks and other features are subject to variation either from age or surroundings. Yet 

 there are certain main features which, with the minute structure of bristles and hooks, 

 are of service in discrimination and arrangement. 



Most authors subdivide this large family into sub-families, and to this there is no 

 objection. The first sub-family is that of the Amphitritea, Malmgren, in which the 

 cephalic lobe is short, provided with numerous grooved tentacles, eye-spots and branchiae. 

 The setigerous processes occupy the lateral regions, especially anteriorly, whilst the hooks 

 occur throughout. 



Sub-Family I. — Amphitritea. 

 Genus OXLIV. — Amphitrite, 0. F. Mutter, 1771. 



Cephalic lobe typical, with numerous sulcate tentacles ; narrow vertical margin behind 

 these produced on each side into a lobe, and under the tentacles forming a membranous 

 lip above the mouth. Buccal segment naked. Branchiae fruticose (or simple filaments), 

 sparingly branched, equal, three pairs, fixed to segments 2, 3 and 4. Setigerous 

 lobe beginning at the fourth segment, under the third branchia, and occurring in segments 

 16 — 24 Tori for the hooks commencing on the fifth segment (second setigerous), and 

 borne behind the bristled region on short subrectangular pinnules. Capillary bristles from 

 the fourth backward with the tips striate and serrulate. Hooks short, avicular, biserial in 

 the bristled segments with the exception of the first six, in the rest uniserial, and having 

 three to four teeth. Ventral scutes conspicuous. This genus belongs to the first large 

 group of the Terebellids, in which the anterior and posterior hooks do not materially differ, 

 the cephalic region is short and eyes often behind the tentacles. Anterior and posterior 

 nephridia present, the former smaller and with narrow, the latter with wider tubes (Hessle). 



Malmgren (1865) first drew attention to the confusion connected with the generic 

 name from 0. F. Muller to Cuvier, Oken and Lamarck, but as Claparede subsequently 

 approved he conserved the old title for the species of 0. F. Muller, viz., Amphitrite 

 cirrata. 



1. Amphitrite cirrata, 0. F. Muller, 1771. Plate CXXV, figs. 5— 5 a — bristle and hook. 



Specific Characters. — Cephalic fold behind the tentacles not produced into lateral 

 lobes. Byes absent. Three pairs of branchiae each arising by a single short base, and 

 consisting of simple filaments tapering a little distally and slightly spiral. Body from 

 87 to 200 mm. in length, and having about eighty-five segments. Seventeen pairs of 



