212 CHITONID^. 



nent : inside smooth and polished, of a greenish cast : notches 

 slight, 5 on the head-plate, 1 on each side of every middle 

 plate, and 2 on the tail-plate, making altogether 19. L. 0-75. 



B. 0-375. 



Yar. 1. attenuata. Much longer and narrower in proportion 

 to the breadth. 



Yar. 2. gracilis. Longer than usual, with finer sculpture : 

 oirdle broader and membranous, sparsely set with spines, and 

 mostly having an extra tuft (occasionally two) at the tail. 



C. gracilis, Jeffreys, in Ann. Nat. Hist. Feb. 1859, p. 106. 



Habitat : Rocks, stones, and oyster- shells, on every 

 part of our coast from low-water mark to 25 f. ; off Mull 

 of Galloway in 145 f., as C. discrepans (Beecliey) . Var. 

 1. Oban (Barlee). Var. 2. Weymouth (Metcalfe and 

 Damon) ; Lul worth (J. G. J.) ; Gronville Bay, Jersey, 

 with C. discrepans (Norman); Milford Haven (M c An- 

 drew and Jordan) ; Lough Strangford (Adair) . A speci- 

 men from the last mentioned locality measures nearly an 

 inch and a half in length, while the largest that I have of 

 the typical form (from Unst) is scarcely an inch long. 

 Fossil in the Coralline Crag, Sutton (S. Wood) ; South 

 Italian tertiarie s (Philippi) . The foreign distribution of 

 this species extends from Finmark (Sars) to the iEgean 

 (Forbes), Barbary (Brander, fide Linne), Morocco 

 (M f Andrew), Algeria (Weinkauff), and Canary Isles 

 (M f Andrew), at depths ranging to 20 f. ; but some of 

 the southern localities which have been published pro- 

 bably belong to C. discrepans. Malm found it attached 

 to Laminaria saccharina on the coast of Bohuslan at a 

 depth of 12 f. The variety gracilis occurs at Etretat, in 

 Normandy (J. G. J.), and in the Loire-Inferieure 

 (Cailliaud). 



This handsome species crawls backwards as well as 

 forwards. Mr. Jordan remarks that it appears much 



