258 HETEROCIRRUS. 



Dalyell (1853) procured about a dozen in a single oyster-shell, and he thought each 

 " capable of forming an enlarged cavity for its own lodgement— it may be by some solvent 

 and the tube is lined with silk." 



Monticelli states that this form is a protandrous hermaphrodite in the Mediterranean 

 but Caullery and Mesnil do not confirm this in the case of specimens in the Channel, 

 where it shows an epitokous condition. On the other hand, in a female example 

 procured by De St. Joseph, and also in one procured by Langerhans, no trace of an 

 epitokous condition was present. 



Cunningham and Ramage 1 (1888) observe that Dodecaceria differs from Chaetozone in 

 (1) the absence of the peculiar arrangement of hooks posteriorly, and (2) in having but a 

 few pairs of branchial cirri and only on the anterior somites. They found it in roots of 

 Laminarige at Granton, not in shells as Johnston did. 



A remarkable case of abnormal regeneration of this species is recorded by Caullery 

 and Mesnil 2 (1897) in which what they supposed to be a fragment of the middle of the 

 body reproduced at the anterior end a head and eleven setigerous segments, as well as a 

 tail on the right side of the cicatrix of thirty-two segments ; whilst the posterior end of 

 the original fragment developed a tail of thirty-one bristled segments. The same 

 talented authors represent the gonaducts of this species as simple funnels opening 

 externally by pores. They also found Gregarines in the digestive tube, viz. Selenidium 

 and an Opalina, probably 0. lineata (Haplitophryx, Stein). 



It is possible that further examination of the American forms of this and other 

 Cirratulida3 may reveal closer relationship with the British forms than Verrill thinks. 



Genus CVTIL — Heterocirrus, Grube. s 



Head devoid of appendages; with or without eyes; first bristled segment bears a 

 pair of large grooved tentacles and a pair of branchial filaments slightly above and 

 behind them ; 4 a pair of lateral branchiae on many of the succeeding segments, but they 

 are rare or cease altogether posteriorly. Capillary bristles and crotchets or capillary 

 bristles only. 



In Heterocirrus ater (Fig. 127) the deeply pigmented hypoderm, which is specially 

 thickened in the mid-ventral region, rests on a thin basement-layer with a few circular 

 fibres internally. The nerve-cords lie at the inner border of the hypoderm, and are more 

 distinct than in Dodecaceria concharum. Moreover, a large neural canal is situated in the 

 centre superiorly. The large oblique muscles are attached over the ovoid area of the cords 

 and cover each slope of the area completely. The ventral longitudinal muscles apparently 

 are the thicker. In transverse section they taper as they approach the nerve-area. The 

 dorsal sinus or blood-vessel is generally largely dilated and filled with granular contents. 

 Large blood-vessels occur inside the body-wall all around, and are especially conspicuous 



1 ' Trans. Eoy. Soc. Edinb./ vol. xxxiii, p. 647, pi. 39, fig. 12. 

 3 ' Zool. Anzeiger/ Bd. xx, p. 438, three text-figs. 



3 This genus is conserved with hesitation, for all the species might fall under Dodecaceria, 



4 Carus says, " between which a short papilliform process occurs." 



