TETRASTEMMA VEKMICULA. 169 



only examined in small examples, and they were very indistinct, but they probably have the same 

 direction as in other species. 



A variety was dredged off St. Peter Port, Guernsey, in 10 fathoms, with the eyes of large 

 size, very pale, and with whitish grains from the tip of the snout backwards between the pairs. 

 The stylet- region had the posterior border of the muscular investment nearly transverse, but pro- 

 bably this was abnormal, as in all other respects it agreed with that of T. Candida. 



This is a very restless species, constantly gliding about with considerable speed ; indeed, it 

 is one of the most active of the group. It is tolerably hardy, and will survive more than twenty- 

 four hours on a moist stone in a room. In Bressay Sound the variety above mentioned 

 abounds amongst Obelia geniculata about half-tide mark, as well as amongst Corallina bored by 

 Leucodore at the extreme verge of high-water. 



Whether the variety shown in Plate III, fig. 5, and having a pale orange hue, will prove to 

 be specifically different on further investigation, I am at present unable to say, as the drawing 

 was the sole remembrance brought by my sister in one of her excursions. It was procured from 

 the deep water off St. Andrews Bay. 



The ova are developed in April and May, as well as in autumn. 



I am inclined to refer the Fasciola Candida of 0. P. Miiller to this common and variable 

 form. It was discovered by 0. Pabricius under stones on the shores of Greenland, and his 

 specimens were unusually large, viz. from two to three inches, the only doubtful feature in the 

 description. (Ersted's Tetrastemma varicolor, again, seems to include both this species and T. 

 dor salis. The occurrence of a single stylet-sac in the example of M. de Quatrefages is purely 

 accidental. The Vermiculus coluber of Sir J. Dalyell is probably a pinkish variety of this form, 

 and not T. melanocepkala. M. van Beneden included this along with others under his 

 Folia obscura, and the Polia farinosa of the same author presents no feature different from the 

 young of this species. M. Claparede's T. varicolor comes under the same head, a view supported 

 by his figure of the stylet -region. This is the only Nemertean mentioned in Maitland's ' Pauna 

 Belgii septentrionalis.' 



4. Tetrastemma vermictjla, JDe Quatrefages. Plate III, fig. 3. 

 Specific character. —A longitudinal dark patch between the eyes of the respective sides. 



Synonyms. 



1846. Polia vermiculus, De Quatrefages. Ann. des sc. nat., 3 me ser., Zool., torn, vi, p. 214. 



1849. „ „ Ibid. Voyage en Sicilie, vol. ii, p. 126, pi. 14, f. 12 and 13. 



1850. Nemertes vermiculus, Diesing. Syst. Helm., vol. i, p. 270. 

 1862. Tetrastemma vermiculus, Ibid. Revis. der Turbell., p. 290. 



1869. „ „ Mcintosh, Trans. Roy. Soc. Edinb., vol. xxv, pt. ii, p. 339 et seq. 



Habitat. — Not uncommon under stones between tide-marks, and occasionally dredged in 

 the laminarian region, from the North of Scotland to the Channel Islands. Coast of France 



(Brehat). 



22 



