OPHELIA LIMACINA. 9 



partial to soft grey mud, and the sluggish Travisia even frequents strongly odoriferous 

 mud, as in the West Voe of Scalloway. The movements of Ammotrypane, Polyophthalmus, 

 and Armandia are active, and some have likened those of Ammotrypane to the swift rushes 

 of the lancelet. 



Genus LXXX — Ophelia, Savigny. Char, emend. 



Head acuminate ; sense-organs retractile. Mouth inferior. Body rounded anteriorly, 

 posteriorly grooved ventrally. Caudal papillae large. Dorsal and ventral fascicles of 

 capillary bristles with a mamilla between. Ligulate branchiae or dorsal cirri in all the 

 following segments; the anus terminal, surrounded by papillae. Corpuscles in blood 

 (Claparede). 



Ophelia was the eighth genus of Savigny's 1 Nereides (1820), and in his description 

 he reversed the annelid, which was found by D'Orbigny on the shores of France, and the 

 description leaves doubt as to its relationship with the common form. 



(Ersted (1844) made this one of the genera of his Ariciae lumbricmm along with 

 Cirratulus, Dodecaceria, Ophellna, and Eumenia, pointing out that the characters had 

 hitherto been badly treated, the dorsal having been mistaken for the ventral surface, and 

 the mouth for the anus. He defined the group as consisting of large, non-pellucid 

 forms, without tentacles, with bifid feet and filiform, ligulate or subramose branchiae. 



Claparede 2 (1868) refers to the structure of the alimentary canal, and points out that 

 (Ersted describes anteriorly a caecum which he considers to be a salivary gland, and De 

 Quatrefages a proboscis, whilst Delle Chiaje thought it was a respiratory vesicle, and 

 Gr. Costa a fleshy heart comparable to the vertebrate organ. Claparede describes and 

 figures the organ in Ophelia radiata as a double conical caecum, the posterior extremity 

 of which lies freely above the oesophagus, the anterior and larger end being fixed to the wall 

 of the body. It forms a double muscular screen between the cephalic region and the 

 perivisceral cavity, arresting the perivisceral corpuscles in their forward flow, and it may 

 be, by its contraction, stiffening, like an injector, the pointed snout of the animal in its 

 movements through the sand. An interesting feature in the circulation is the presence 

 of numerous blind branches of the dorsal vessel in the cephalic region in front of the 

 muscular caecum. 



1. Ophelia limacina, H. Rathlce, 1843. Plate LXXXVIII, fig. 1; Plate XCV, figs. 1 



and 1 d — head and tail ; Plate CM — bristle. 



Specific Characters. — Head a pointed cone. Mouth opposite the first bristle-bundle. 

 Body 2 — 2-J inches long, somewhat fusiform, more massive than in Ammotrypane aidogaster, 

 enlarged in the anterior third, deeply grooved ventrally throughout the rest of its extent, 

 the ventral longitudinal muscles forming prominent lateral ridges bearing the feet, which 

 are about thirty-four in number; the first ten have the pale iridescent bristles supported 

 by a fillet in front and behind, but at the eleventh the posterior fillet is dorsally much 



1 < Syst. Annel./ pp. 3, 12, 38. 



2 < Annel. Nap./ p. 289. 



125 



