ACANTHOCHITES. 11 



Back subcarinated, blackish ; margin wide, tuberculate ; tufts 

 white, bronzed. The back is oblong, blackish, bordered by a wide 

 tuberculous band ornamented with bunches of white or bronze hairs. 

 Length 15 mill. Animal light red ; head rounded, gills reddish, etc. 

 (jRiwo.) 



Balearic Is. (Hidalgo) ; Nizza (Risso) ; Genoa (Issel) ; Gorgona 

 (Caifassi); Naples; Palermo (Monts.) 



Acanthochites ceneus Risso, Hist. Nat. de 1'Eur. Merid. iv, p. 269 

 (1826). CARTJS, Prodromus Faunae Mediterranese ii, pt. 1, p. 182 

 (1889). Chiton (Acanthochites^ ceneus MONTEROSATO, Journ. de 

 Conchyl. 1878, p. 147. Chiton gracilis JEFFR., Ann. Mag. N. Hist. 

 (3), iii, p. 106, t. 3, f. 9a, b (1859). SOWB., Illustr. Index Brit. Sh., 

 t. 10, f. 6. C. fascicularis var. gracilis JEFFR., Brit. Conch, iii, 

 p. 212. 



With this form Monterosato identifies C. gracilis Jeffreys, the 

 description which follows : 



" C. fascicularis var. gracilis Jeffr. PI. 4, fig. 83. 



Longer than usual, with finer sculpture; girdle broader and 

 membranous, sparsely set with spines and mostly having an extra 

 tuft (occasionally two) at the tail. 



Weymouth and off Milford Haven. Dredged in deep water. 



Differs from A. fascicularis in being slender, the girdle more 

 sparsely pilose, and having one or two tufts behind the posterior 

 valve, 19 or 20 tufts in all. The granulation of valves is finer than 

 in fascicularis, coarser than in discrepans. As I have seen no 

 Mediterranean specimens I cannot affirm their identity with those of 

 the south of England ; but they are probably the same. The 

 Mediterranean form has not been figured. Jeffreys in his later writ- 

 ings considered this a delicate deep-water form of fascicularis, a con- 

 clusion with which I am disposed to coincide. Further study with 

 abundant material from the Mediterranean and Atlantic is necessary 

 to establish the true status of the form. 



The form described by Rochebrune as A. hamatus is probably a 

 synonym of A. ceneus. The original description follows: 



Acanthochites hamatus Rochebr. Shell elongated, ovate, roseate, 

 intensely carinated, the carina very high, linear, rugulose, posteriorly 

 acute. Anterior valve rounded, intermediate valves with the lateral 

 areas intensely granulated all over, the grains polygonal, flattened, 

 subumbilicated. Marginal ligament pale rufous, with 9 shining 



