416 CHITONID.&. 



ture, or elevation. The hinder valve is both short and 

 narrow ; it is slightly and indistinctly submarginated at its 

 extremity. The connecting ligamental margin is cori- 

 aceous, very narrow in the young (where the thin edge 

 contracts extremely in drying), and but moderately broad, 

 in proportion to the wideness of the plates, in the adult, 

 the two edges together averaging, at the fifth valve, even 

 in the large Scotch examples, only about two-sevenths of 

 the breadth of that plate. The colouring consists of linear 

 zigzag markings, flammules, or angular spots of white, 

 greenish, or flesh-colour, upon a ground of rufous or 

 Turkey red, with the posterior edge often prettily articu- 

 lated with darker tinted and white spots, or vice versa, 

 the pale colours preponderating ; the leathery margin is 

 either of an uniform fulvous brown, or barred with dusky 

 olive upon a tawny ground. Mr. Lowe states that the 

 first plate is furnished with nine broad teeth, the last with 

 eight broad ones; the intermediate valves with two on each 

 side. The Itevigatus of Macgillivray (Moll. Aberd. p. ] 85), 

 with a granulated border, is evidently not the species so 

 named, but possibly a young asellus. Scotch specimens are 

 occasionally found seventeen lines broad and eleven long, 

 and sometimes even of still larger dimensions ; English 

 individuals are much smaller. 



The animal, according to Middendorff, has its range of 

 branchial leaflets extended to half the entire length. There 

 are about twenty-four on each side, placed rather distant 

 from each other. 



This is one of our rarer and more local Chitons as well 

 as the finest species we possess of the genus. It is essen- 

 tially a northern form. In the north-east of England it 

 has been taken at Scarborough (Bean); among rocks below 

 Dunstanborough Castle, very rare (Embleton) ; a single 



