TETRASTEMMA MELANOCEPHALA. 165 



1. Tetrastemma melanocephala, Johnston. Plate II, fig. 1. 



Specific character. — A large mass of black pigment between the eyes. Marginal stylet-sacs 

 placed considerably in front of the central apparatus. 



Synonyms. 



1808. Planaria unipimctata, Montagu. MS., p. 236, tab. 55, f. 5. 



1837. Nemertes melanocephala, Johnston. Mag. Zool. and Bot., vol. i, p. 535, pi. 17, f. 5. 



1842-3. „ „ (Ersted. Kroyer's Naturhist. Tidskr., iv, p. 577. 



1844. „ „ Ibid. Entwurf. Plattw., p. 88. 



1846. Prostoma melanocephala, Johnston. Ann. Nat. Hist., vol. 16, p. 436. 



„ Nemertes melanocephala, W. Thompson. Ann. Nat. Hist., vol. xviii, p. 387. 



„ Polia coronata, De Quatrefages. Ann. des sc. nat., 3 me ser., Zool., torn, vi, p. 213. 



„ ,, pulchella, Ibid. Op. cit., p. 214. 



1849. „ coronata, De Quatrefages. Voyage en Sicilie, vol. ii, p. 125, pi. 13, f. 6—9. 

 „ „ pulchella, Ibid. Op. cit., p. 126, pi. 16, f. 7 and 8. 



1850. (Erstedia pulchella, Diesing. Syst. Helm., vol. i, p. 248. 

 „ Nemertes melanocephala, Ibid. Op. cit., p. 270. 



„ „ coronata, Ibid. Op. cit., p. 271. 



1859. Loxorrhochma coronatum, Schmarda. Neue wirb. Thiere, i, i, p. 39. 

 1862. Tetrastemma menalocephalum, Diesing. Revis. der Turbell., p. 291. 



„ Loxorrhochma coronatum, Ibid. Op. cit., p. 295. 



1865. Omatoplea melanocephala, Johnston. Catalogue Brit. Mus., p. 23, pi. na, f. 5 and 5*. 



1866. „ „ Lankester. Ann. Nat. Hist., 3rd ser., vol. 17, p. 388. 



1867. Cephalotrix unipunctata, Parfitt. Catal. Annel. Devonsh., p. 5. 

 „ Omatoplea melanocephala, Ibid. Ibid., p. 7. 



1868. Ommatoplea „ Mcintosh. Ann. Nat. Hist., 4th ser., vol. ii, p. 293. 



1869. „ „ Ibid. Trans. Boy. Soc. Edinb., vol. xxv, pt. ii, p. 333 et seq. 



Habitat. — Under stones between tide-marks, in crevices of rocks near low-water mark, and 

 ranging to twenty fathoms off Guernsey. Coast of France, and Sicily. 



Body two to two and a half inches in length, somewhat flattened in progression, rounded in 

 contraction, gently dilating behind the head, then continuing of almost equal calibre until near 



the tail. 



Colour dull yellow, greenish yellow, or dull green ; occasionally with minute brownish pig- 

 ment-grains along the sides. A large and somewhat quadrate black patch on the snout, in some 

 cases with one faintly marked band of white pigment in front, and another— more distinct— 

 posteriorly. In a specimen from deep water off Guernsey the dark spot on the head was nearly 

 invisible, and the whitish pigment indistinct. The fluid in the proboscidian sheath causes a pale 

 streak along the centre of the dorsum. 



Head flattened, much wider than the succeeding portion of the body, famished with a notch 

 in front. The first two eyes are placed some distance behind the tip of the snout, and incorpo- 

 rated with the anterior border of the black patch, so that they are not at first observed. The 

 posterior eyes lie quite behind the pigment-patch, the white band, when present, intervening. 



