LINEUS BILINEATUS. 191 



fissures, which are rather shallow. Eyes forming a nearly parallel row on each side, distinctly 

 separated, and to the number of six or eight in each row r . They are not symmetrically arranged, 

 and a considerable translucent space exists between their commencement and the tip of the 

 snout. The mouth is situated much further back than in Lineus sanguineus, to which it is other- 

 wise closely related. 



Seven or eight specimens were sent me, in October, 1866, by Mr. Parfltt, of the Devon and 

 Exeter Institution, in a tin box, and a few are still alive (Dec, 1871), so that they exhibit the 

 usual hardihood in confinement. In progression the head is often ribbed in a longitudinal 

 manner. When irritated, the extended worm contracts, generally in a spiral or closely coiled 

 manner, and sometimes in a form so regularly twisted as to resemble a rope with its strands. It 

 advances by gentle undulations of the body, and frequently the head is rolled from side to side. 

 The worm also readily forms itself into a knotted mass, as well as stretches to an extreme degree 

 of tenuity. The skin presents an acid reaction. 



This is one of the many discoveries made by the acute and persevering Montagu on the 

 southern coast. There are few external characters in the description of the animal that had 

 escaped him. It is doubtful whether Prof. Grube's Nemertes lactea from Villafranca ('Archiv 

 fur Naturges.,' 1851, p. 151, taf. 7, f. 3 and 4) coincides with our species. His enlarged 

 drawing of the head has certainly many more eyes, and the orange specks on the dorsum are quite 

 different. Moreover, it is scarcely to be supposed that this author would not mention so impor- 

 tant a point as the distance of the mouth behind the ganglia. He states that the " mouth is 

 rounded/' and about two millimetres from the snout. Dr. Johnston's preparation of Lineus 

 aldus, Dalyell, in the British Museum, resembles the present species very closely. 



5. Lineus bilineatus, Delle Chiaje. Plate VI, fig. 1. 



Specific character. — Head rather rounded anteriorly ; eyeless. Body pale brown or dull 

 pinkish, with a white stripe on each side of a dorsal median line. 



Synonyms. 



1841. Folia bilineata, Delle Chiaje. Descr. e Notom. deglianim. invert., torn, hi, p. 126, tab. 103, f. 11 



and 12. 



1844. Nemertes bilineata, (Ersted. Entw. Plattw., p. 91. 



1850. Meckelia bilineata, Diesing. Syst. Helm., vol. i, p. 264. 



„ „ cerebratulus, Ibid. Op. cit., p. 269. 



1853. Gordius taenia, Dalyell. Pow. Creat., vol. ii, p. 70, pi. 10, f. 1 — 4. 



1860. Cerebratula (Erstedii, Van Beneden. Eecher. sur les Turbell., p. 16, pi. 2, f. 1—4. 



1862. Cerebratulus bilineatus, Ibid. Op. cit., p. 273. 



„ Meckelia (Erstedii, Diesing. Revis. der Turb., p. 286. 



„ „ cerebratulus, Ibid. Op. cit., p. 286. 



1865. „ taenia, Johnston. Catalogue Brit. Mus., pp. 28 and 298. 



1866. „ „ Lankester. Ann. Nat. Hist., 3rd ser., vol. xvii, p. 389. 



1868. Cerebratulus taenia, Mcintosh. Kept. Brit. Assoc, 1858, p. 340. 



1869. „ bilineatus, Ibid. Trans. Roy. Soc. Edinb., vol. xxv, pt. ii, p. 374 et seq. 



