318 MYXICOLA AISTHETICA. 
Habitat.—Plymouth (Allen). 
Mediterranean (Claparéde), shores of Cantabria (Rioja). 
The cephalic plate presents the same mid-dorsal process, and the smaller mid-ventral as 
in the type, and the branchial filaments differ only in the more broadly webbed and shorter 
tips and in the absence of the deep brown coloration. Considerable variation, however, 
appears to exist in this respect in the genus. The number of the filaments is eight on each 
side, and the attenuate condition of the pinne differentiates them from most Sabellids proper. 
The body is about an inch in length, slightly diminished anteriorly, more distinctly 
tapered posteriorly, and without terminal appendage, the eyes (about seven), which are 
absent in preparations, forming a semicircle within the tip. 
The anterior bristles are long, pale, and slender, and it was not always easy to 
demonstrate the presence of the slightly winged tip (Plate CXXXII, fig. 8). They, 
however, keep to the type, though in a modified degree as compared with M. infundibulum, 
the winged region being short and narrow. The posterior bristles are somewhat shorter 
than the anterior, and the winged region at the tip is more minute. 
The anterior hooks are few in number in each group, and, so far as could be observed, ~ 
had simple, straight shafts, with a trace of an enlargement below the hooked tip (Plate 
CXXX, fig. 5). They tapered gently from the base to the slight swelling in the neck, 
followed by the curve of the hook at the tip. They thus differed from Claparéde’s figure, 
which would pass for the hook of an Oligochet. 
The posterior hooks (Plate CX XX, fig. 5a) had a base vertically elongate, convex at 
the anterior outline and nearly straight posteriorly. A single tooth occurs above the main 
fang. | 
Whilst the former species of Myzicola is found on a sandy bottom with Branchiomma 
vesiculosum, this form occurs with colonies of Hydroides. . 
Miss Bush’s' Myzicola affinis has certain resemblances to this form, though the descrip- 
tion and figures leave doubt. Her Myzicola glacialis from Unalaska Island, embedded in 
much mucous under and between stones on shelly sand, has long simply curved hooks like 
M. esthetica, a species to which she does not allude. 
Claparéde’ (1870) instituted a new genus (Leptochone) and species (L. cesthetica) for 
this form, which he found plentifully in the haunts of Amphiglena and Fabricia in mucous 
tubes on algze, founding the distinctions on the paucity of the anterior uncini, on the shape 
of the posterior hooks and the semilunar “‘ antenne ” (tentacles). He held that the form 
was intermediate between Amphiglena and Myzicola. He noted the peculiar form of the 
three pairs of anterior hooks, the absence of tori, and their replacement by an epithelium 
of polygonal granular cells, the cilia of the branchial fan and the filiform terminal processes 
the lateral eyes and the several statocysts. He describes the “ cartilaginous ” axis of the 
branchial filaments, but this term is now generally replaced by mucoid or chordoid. The 
sillon copragogue is absent. 
It may be a question whether the specimens from the Channel Islands and Plymouth 
refer to that of Claparéde, since no pigment was visible in the preparations, and Claparéde’s 
figure of the anterior crotchet differs much. . 
1 «Tubic. Annel. Pacific,’ p. 218, pl. xxxviii, figs. 17—20, 1905. 
? “Suppl. Annél. Neap.,’ p. 149. 
