LOIMIA MONTAGUI. 147 



tips. Rows of hooks commence on the second segment and extend throughout the body. 

 Hooks pectinate with a long anterior border with five or six teeth ; opposed back to back 

 in the double rows (Fauvel). Statocysts in the second segment (Fauvel). Nephridia as 

 in Lanice. 



1. Loimia MONTAGur, nom. nov. Plate CXIX, fig. 5— body; Plate CXXVI, figs. 1 and la 

 — bristle and hook, and 1 b — hook of L. medicsse, Sav, 



Specific Characters. — Cephalic lobe has a small dorsal collar which does not join the 

 fan-like supra-oral arch. A large lamella, with a slight median excavation, forms a great 

 post-oral platform, which is differentiated into a median, more flexible region and two 

 stiffer lateral regions. Immediately behind is the first pair of gills ; a broad fan-shaped 

 flap occurs midway between the second pair and the ventral scute. The fourth segment 

 bears the third pair and the first bristle-bundle. Ventral scutes not separated by deep 

 furrows, and end in a narrow ridge about the eleventh bristle-bundle. Segments marked 

 by narrow rings. General colour yellowish, ventral scutes rufous, shaded with purplish 

 black (Montagu). Seventeen pairs of setigerous processes, commencing on the fourth seg- 

 ment; bristles commencing on the fifth segment, pale, smooth, golden, with tapering 

 winged tips. Hooks pectiniform, with a long anterior border and five to six teeth, 

 and no process exists on the edge of the base beneath the great fang as in L. medusas 

 from the Mediterranean. Posterior region has from 80 to 130 segments. 



Synonyms. 



1818 ?. Terebella constrictor, Montagu. Linn. Trans., vol. xii, p. 344, Tab. xiii, fig. 2. 

 1915. Loimia gigantea, Mcintosh. Ann. Nat. Hist., ser. 8, vol. xv, p. 17. 

 „ „ medusas, Allen. Journ. M. B. A., vol. x, p. 636. 



Habitat. — Devon coast, as Terebella constrictor (Montagu) ; Plymouth (Baird) ; 

 Plymouth (Spence Bate and B. Eowe) ; Yealm shore, Plymouth (Allen). 



The cephalic lobe presents a small and inconspicuous dorsal collar which at each 

 side bends down to disappear in the general plate, and without joining the supra-oral 

 arch, which is fan-shaped and projects little. The space between the latter and the 

 cephalic collar is occupied by the grooved tentacles. From the outer border of the 

 cephalic region a large lamella arises, and passes with a slight median excavation to the 

 other side, forming thus a great post-oral platform. A differentiation on each side occurs 

 in the form of a curved line which extends from the segment- junction posteriorly 

 obliquely forward and outward, thus marking off a central and more flexible region and 

 two stiffer lateral regions. The great development of this post-oral flap is characteristic 

 of the species. 



The body has the typical Terebellid outline, enlarged in front, and tapering gradually 

 to the posterior anus. It is rounded dorsally, flattened ventrally in front, and slightly so 

 posteriorly. 



The segment succeeding that bearing the post-oral lamella bears the first pair of 

 branchiae, but is not distinguishable in the sole example available from the next segment 



