202 ARICIAD^. 



the anterior portion a dusky green, with red cross lines. Very- 

 fragile. 



Dr. Williams mentions a Nerine marcella, Rep. Brit. Assoc, cit. 

 214, 234; and Sars queries whether his Nerine foUosa is synony- 

 mous with the " Spio coniocephalm, Johnst.," Adriat. Havs Fauna, 

 p. 15. As there is no species with the latter name, we presume 

 Sars means Nerine coniocephala. 



Plate XVII. Fig. 9. Nerine coniocephala, of the natural size, the tail 

 wanting. The specimen was one of unusual size. 10. The proboscis, 

 1 1 . An antenna magnified. 12. Oue-lialf of a cross section of an ante- 

 rior segment. 13. A similar view of a segment from near the middle. 



The following worm may belong to the genus : — 



Nereis contorta. 



Nereis contorta — the spiral Nereis, Dalyell, Pow. Creat. ii. 156. pi. 20. 

 f. 19, 20. 



Desc. " Length half an inch. Body round, slender, composed of 

 numerous segments. Two large and long cartilaginous-looking an- 

 tennce on the head. A pencil of hristles issues from a papilla on 

 each side of the segments, together with a spine of some length towards 

 the back. No eyes could be discovered. This animal generally lies 

 in so close a coil, that it is very difficult to ascertain its true figure, 

 especially that of the posterior part, which has a short funnel-shaped 

 margin." — Dalyell. — Is it Leucodore cceca 1 — See Grube, Fam. An- 

 nel. 67. 



24. SPIO. 



Spio, Turt. Gmel. iv. 81. Mont. Test. Brit. xxix. Lam. An. s. Vert. 

 v. 318. Blainv. in Diet, des Sc. nat. Ivii. 440. Oersted, Annul. 

 Dan. Consp. 39 ; Groenl. Annul. Dorsibr. 50. 



Char. Body filiform : head subquadrangular or conical, with a 

 central lobe produced in front : eyes four, in a square : antennae two, 

 sincipital, much elongated and cornuted : segments incised at their 

 sutures, all nearly similar : feet prominent, furnished with a superior 

 branchial cirrus, a shorter inferior cirrus, and with two setigerous 

 tubercles, — the upper with setaceous and hooked bristles, the infe- 

 rior with setaceous bristles only (No. XXXVI. figs. 1, 2, 3) : branchial 

 cirri undivided, flattened, reflected dorsally, veined and ciliated : 

 anal segment with two short styles and a pair of inferior cirri. 

 Tubicolous and arenicolous. 



1 . Sp, filicornis, the branchial cirri of the anterior segments largest, 

 and gradually lessening on the posterior segments; antennae 



