172 TETRASTEMMA DORSALIS. 



specimens of this species under his Folia obscura. In the absence of more definite characters I 

 have not thought it proper to place the Tetrastemma sanguirubra of Stimpson amongst the 

 synonyms. 



6. Tetrastemma dorsalis, Abildgaard. Plate I } fig. 4, and Plate III, fig. 4. 



Specific character. — Body short, thick and round, little tapered towards either extremity. 

 Speckled with yellow and brown, or with a single dorsal stripe. 



Synonyms. 



1806. Planaria dorsalis, Abildgaard. Zool. Danic, vol. iv, p. 25, tab. 142, f. 1 — 3. 



1844. Tetrastemma fuscum, (Ersted. Kroyer's Naturhist. Tids., iv, p. 575. 



„ „ „ Ibid. Entw. Plattw., p. 86, woodcut 14. 



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



1846. (Erstedia maculata, De Quatrefages. Ann. des sc. nat., 3 me ser., Zool., torn, vi, p. 222, tab. 8, f. 2. 



„ „ tubicola, Ibid. Op. cit., p. 223. 



1849. „ maculata, Ibid. Voyage en Sicilie, vol. ii, p. 134, pi. 17, f. 15 — 17. 

 „ „ tubicola, Ibid. Op. cit., p. 135, pi. 17, f. 18 and 19. 



1850. „ maculata, Diesing. Syst. Helm., vol. i, p. 247. 

 „ „ tubicola, Ibid. Op. cit., p. 247. 



„ Tetrastemma fuscum (partim), Ibid. Op. cit., p. 257. 



„ „ varicolor (partim), Ibid. Op. cit., p. 257. 



1853. Vermiculus variegatus, Dalyell. Pow. Creat., vol. ii, p. 91, pi. 10, f. 25 and 26. ! 



1859. Tetrastemma variegatum, Leuckart. Archiv fur Naturges., ii, p. 188. 



1862. (Erstedia maculata, Diesing. Revis. der Turbell., p. 263. ' 

 „ „ tubicola, Ibid. Op. cit., p. 263. 



„ Tetrastemma fuscum, Ibid. Op. cit., p. 289. 



1863. „ variegatum, Ibid. Nachtrage zur Revis. der Turbell., p. 10. 



„ „ marmoratum, Claparede, Beobach. iiber Anat. u. Entwicklung., &c, p. 24, taf. 5, 



f. 14. 



1865. „ variegatum, Johnston. Catalogue Brit. Mus., pp. 20 and 289. 



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



1868. „ „ Mcintosh. Rept. Brit. Assoc, 1868, p. 340. 



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



Habitat. — Abundant in the laminarian region, in three to ten fathoms, where it haunts 

 Ceramium rubrum and other algae. It is also occasionally found under stones at extreme low 

 water. Extends from Shetland to the Channel Islands. 



Body half to three quarters of an inch in length, and rather more than half a line in 

 breadth. It is so round as to be nearly circular in transverse section, with the exception of a 

 little flattening on the ventral surface ; very slightly tapered at either extremity. 



Colour. — On the coasts of Scotland two varieties are especially common. The most abun- 

 dant form is of various shades of brown or reddish-brown, speckled with groups of yellowish- white 

 granules, often of considerable size, which are placed along the centre of the dorsum from one 



