TETRASTEMMA. — BORLASIA. 21 



15. BORLASIA*. 



Borlasia, Johnston in Mag. Zool. Sf Bat. i. 536. 

 Nemertes, Oersted, Entw. Plattw. 88. 



Char. Body linear-elongate, contractile, somewhat compressed, 

 soft, even and continuous : head indistinctly defined, sometimes with 

 a fissure on the sides : eyes four to sixteen, separate and submar- 

 ginal : mouth terminal, the oesophagus unarmed with horny stylettes. 



1. B. olivacea, linear-elongate, tapered posteriorly, of a dark olive - 

 colour with a red spot in front ; eyes from four to eight. Length 

 3-6"; breadth 1'". 



Planaria bioculata, Johnston in Zool. Journ. iv. 56. 



Nemertes (Borlasia) olivacea, Johnston in Mag. Zool. 8f Bot. i. 536. 



pi. 18. f. 1. Oersted, Entw. Plattw. 89. Dies. Syst. Helm.i. 273. 

 Borlasia olivacea, Johnston in Ann. Sf Mag. Nat. Hist. xvi. 434. 



W. Thompson in lib. ibid, xviii. 388. 



Hab. Between tide-marks. 



2. B. octoculata, of a uniform light reddish-brown colour; eyes 

 six to eight, placed in opposite pairs on the sides of the head. 

 Lengths"; breadth IV". 



Planaria octoculata, Johnston in Zool. Journ. iv. 56. 



Nemertes (Borlasia) octoculata, Johnston in Mag. Zool. Sf Bot. i. 537. 



pi. 18. f. 2. 

 Borlasia octoculata, Johnston in Ann. Sf Mag. Nat. Hist. xvi. 434. 



W. Thompson in ibid, xviii. 388. 

 Nemertes octoculata. Oersted, Entw. Plattw. 91. Dies. Syst. Helm. 



i. 276. 



Hab. Under stones, between tide-marks. 



3. B. purpurea, narrowed at both ends, of a imiform purplish-red 

 colour, paler underneath; eyes six to eight, marginal. Length 

 2-3"; breadth 1"'. 



Nemertes (Borlasia) purpurea, Johnston in Mag. Zool. Sf Bot. i. 537. 



pi. 18. f. 3. W. Thompson in Ann. Sf Mag. Nat. Hist, xviii. 388. 

 Nemertes purpurea. Oersted, Entw. Plattw. 91. Dies. Syst. Helm. 



i. 275. 

 Borlasia purpurea, Johnston in Ann. Sf Mag. Nat. Hist. xvi. 434. 



Hab. Between tide-marks, at the roots of algse and corallines. 

 (a) Berwick Bay, Dr. Johnston. 



4. B. gesserensis, Hnear, obtuse at the ends, greenish, sometimes 



* This name was substituted for the Linens of Simmons by Oken in 1815. It 

 has been since used, in other applications, as a generic appellation, and ought, 

 perhaps, to be discarded. 



