TETRASTEMMA CANDIDA. 



167 



Fig. 12. 



Colour a uniform dull pinkish or pinkish-brown, marked on the dorsum by three stripes — 

 a central white and two lateral brown belts. The latter commence at a ring of the same colour 

 which surrounds the posterior boundary of the snout, and proceed backwards 

 to the tail, where they join ; and the central white line follows a similar course. 

 They are not close to each other, but a stripe of the usual ground-colour of 

 the dorsum intervenes. The abdominal surface has a pale pinkish-brown 

 hue throughout, with the exception of the ventral portion of the brown ring 

 in front. 



Head wider (in its greatest transverse diameter) than the succeeding 

 portion of the body, spathulate, furnished with four black eyes, the anterior 

 pair of which is the larger, while the posterior specks are closer and just in 

 front of the transverse pigment-belt. The mouth is a well-marked longitudinal 

 slit, in the usual position on the ventral surface. 



Cephalic furrows. — These pass inwards and backwards from the prominent 

 angles of the snout on the dorsum towards the posterior pair of eyes. The 

 lateral notch is seen on the ventral surface, but the direction of the furrows 

 thereafter (if such exist) is indistinct. 



In a pale example from Shetland the brown ring anteriorly appears only 

 on the dorsum, and the central white line is somewhat faint. In the coloured 

 drawing (Plate III, fig. 1) only two eyes are visible, the posterior pair being 

 covered by the great development of the pigment-belt. The ordinary 

 condition is represented in the woodcut fig. 12. 



CErsted describes a Tetrastemma bioculata, but the snout in his species is peculiarly 

 acuminate, and he indicates no stripes or other colouring of note. 



Dorsal view of the an- 

 terior region of Te- 

 trastemma Bober- 

 tiance. Enlarged. 



3. Tetrastemma Candida, 0. F. Mutter, 1774. Plate II, figs. 2 and 3. 



Specific character. — Head flattened, wider than the rest of the body ; eyes distinct. Stylets 

 large. Colour pale yellow, greenish, or reddish. 



Synonyms. 



1774. Fasciola Candida, O. F. Muller. Verm, terrest. et fluv. hist., i, ii, p. 71. 



1776. Planaria Candida, Ibid. Zool. Dan. Prodr., p. 223, No. 2704. 



1780. „ „ O. Fabricius. Fauna Grcenlandica, p. 327. 



1788. „ }i Linnaeus (Gmelin). Syst. Nat., torn, i, pars vi, p. 3094. 



1798. „ „ O. Fabricius. Skrivt. af Naturhist. Selskab., iv, p. 62, tab. 11, f. 11 



1828. „ „ Bosc. Hist. Nat. des Vers., i, p. 262. 



1829. Planaria quadrioculata, Johnston. Zool. Jour., vol. iv, p. 56. 



1837. Nemertes quadrioculata, Ibid. Mag. Zool. and Bot., vol. i, p. 535, pi. 17, f. 4. 



„ Tetrastemma varicolor (partim), CErsted. Kroyer's Naturhist. Tids., iv, p. 575. 

 1844. „ candidum, Ibid. Entw. Plattw., p. 88. 



„ „ varicolor (partim), Ibid. Op. cit., p. 85, f. 41 and 44. 



„ „ „ Ibid. De Region, marin., p. 79. 



