26 TERETULARIA. 



2. L. gracilis, cylindrical, tapering to the anal extremity, of a dark 

 umber colour, with a few longitudinal white lines ; head continuous 

 with the body, slightly quadrilobate ; subcervical aperture small 

 and rounded. Length 3" or more ; breadth 4'". 



Nemertes gracilis, Goodsir in Ann. Sf Mag. Nat. Hist. xv. 378 & 383. 



pi. 20. f. 3. 

 Lineus gracilis, Johnston in Ann. Sf Mag. Nat. Hist. xvi. 435. 

 Meckelia gracilis. Dies. Syst. Helm. i. 268. 



Hab. The coralline region. 



3. L. lineatus, cylindrical, tapered posteriorly, marked with faint 

 circular wrinkles, of an olive colour, with several parallel equidistant 

 pale lines along the body ; head small, semiovate, obscurely quadri- 

 lobate, the mesial furrows indistinct, the lips white ; subcervical 

 aperture round. Length 6" ; breadth 2-3'". 



Hab. The sea- shore. 



Obs. There are at least six lines on the dorsal surface, and one or 

 more on the ventral, which are sometimes almost imperceptible. 

 The head is small, and may be almost entirely retracted. 



(a) South Devon, J. E. Gray, 



(b) Berwick Bay, Dr. Johnston. 



4. L. murenoides, flattish, closely wrinkled with rugose striae, nar- 

 rowed posteriorly, of a blackish-green colour with a paler mesial 

 line ; head small, distinct, semiovate, obtuse, with a deep fissure on 

 each side, and a shallow mesial groove on the dorsum and ventral 

 side ; rim of the mouth white ; subcervical aperture large and 

 ovate. Length 3-6" ; breadth 6'" ; thickness 2". 



Plate I. 



Ophiocephalus murenoides, D. Chiaje, An. s. Vert. Nap. pi. 62. f. 6, 7, 

 & 13-15. Dies. Syst. Helm. i. 277. 



Hab. The shore near low water. 



Obs. Larger than L. longissimus, and perhaps not inferior in 

 length. It is less brittle. 



(a) Black-rocks, Leith, Dr. Greville. 



(b) Holy Island, Dr. Johnston. ; 



(c) Berwick Bay, Dr. Johnston. 



(d) No locality. 



(e) Falmouth, W. C. Cocks. 



5. L. fasciatus, flattish, wrinkled circularly with rugose strise, 

 tapered posteriorly, of a yellowish-grey, with a dark fascia on each 

 side and a mesial line on the space between them ; ventral surface 

 yellowish-grey unlineated ; head spathulate, narrow, depressed, with 



