252 CIRRATULUS CIRKATUS. 



bristles, which are more conspicuous than in front. So far as observed the hooks of the 

 dorsal division posteriorly are slightly more slender and less curved than those in the ventral. 



Reproduction. — Those from Guernsey and Herm in July and August had well- 

 developed ova. 



Reproduction of lost parts is common in this species, both head and tail being 

 readily regenerated. An example from the Channel Islands has a small, pale, and some- 

 what triangular snout, without trace of eyes ; and the tentacles arise from a pigmented 

 area, separated only by a narrow pale space, which probably represents the two achaetous 

 segments. The mouth at this stage was an irregular puckered aperture. 



A minute crustacean parasite occurred on the dorsum of an example from Guernsey, 

 attached by the pointed anterior region, and with the swollen posterior part projecting 

 from the surface. Unfortunately in its transit to Dr. Thomas Scott it was lost. 



The Terebella meleseta of Montagu refers to this species. 



There is nothing specifically characteristic in the figure of Dalyell (1853), though it 

 has been included in the present species. He probably did not discriminate it from 

 C. tentaculatus. He mentions that it is nocturnal, and deposited ova in May or June. 



The Girratulus fragilis of Leidy 1 (1855) may be this species or a closely allied 

 form. 



Cunningham and Ramage (1888) found this species depositing the reproductive 

 elements at the end of March, the ova and sperms escaping from the apertures of the 

 segmental organs throughout nearly the whole length of the body. The females were 

 considerably larger than the males, viz. 9 cm. to 5*5 cm. They structurally differentiate 

 the tentacular and the branchial cirri, the former having a single vessel, the latter two. 

 They also allude to the heart-body, though this name is not applied to it. 2 Keferstein, 

 Claparede, Cosmovici, and Cunningham have described the segmental organs of the 

 group. In this species Cunningham found both a large anterior pair of organs and a 

 series in the middle and posterior regions. The nephrostome of the first opens into the 

 cavity of the buccal segment, and externally beneath the ventral division of the second 

 segment. The posterior organs are smaller and simpler, appearing at the twelfth 

 segment, and continuing to the posterior end. 



Girratulus, fragment, Lochmaddy, North Uist. 



An injured fragment of a large Girratulus was procured between tide-marks at 

 Lochmaddy in August, 1865. As no crotchets are present in the region, apparently the 

 posterior, it may belong to the first series of De St. Joseph without such organs, and 

 including G. chrysoderma of Claparede. There are about eighty bristled segments in the 

 fragment. The pale yellow bristles are slightly longer dorsally than ventrally, and are 

 slender tapering capillary forms with hair-like tips ; the branchiae appear to go backward 

 almost to the tip of the tail, if such is diagnosed correctly. 



1 ' Invert. Fauna Rhode Isl./ etc., p. 147, pi. xi, figs. 39 — 43. 



2 They describe the " corduns bruns" of Claparede as in the interior of the dorsal blood-vessel, 

 but not continuous with its wall. In structure these cords are glandular, having elongated granular 

 cells placed perpendicularly to the interior of the cord, which is enclosed by a very thin basement- 

 membrane. These cords end anteriorly at a point where the lateral vessels from which the afferent 

 trunks to the branchiae are given off ('Trans. Roy. Soc. Edinb.,' vol. xxxiii, p. 643). 



