Acanthochites.] AMPHINEURA. 27 



minutely crenulated, squarish ; sutural laminae low, flatly convex ; 

 the tegmentum overreaching the articulamentum posteriorly. 



Length, 28 mm. ; breadth, 12 mm. Divergence, 105. 



Dentition. Button, T.N.Z.I., xv, 129, pi. 16. f. G. 



Type, from the French Pass, in Mus. Hist. Nat., Paris. 



Hab. Found almost everywhere along the coasts of New Zea- 

 land ; more common in the south. Not found outside New Zealand 

 waters. 



Remarks. The largest and finest specimens I found in Dunedin 

 Harbour. Very variable in colour. 



Fossil in the Pliocene. 



Sect. 2. CRYPTOCOXCHUS, Blainville and Guilding, 1829. 



Cryptoconchus (Blainville MS. in Brit. Mus.), Guilding, Zool. Journ.. \, 

 1829. 28. Type : C. porosus, Burrow. 



Valves entirely covered by the girdle, except a linear area at the 

 ridge of each. Posterior valve having the insertion plate with several 

 (5-7) slits, anterior valve with 5 slits. Girdle leathery, naked, bearing 

 a series (18) of sutural tufts on tubercles or pores, sometimes sub- 

 obsolete, along the sides of the valves. Gills extending along the 

 posterior half of the foot. (Pilsbry.) 



Only two species of this section are known the type from New 

 Zealand, and a species from the coast of Florida. 



2. Acanthochites porosus, Burrow, 1815. Plate 2, fig. 10; Plate 4, 

 fig. 2. 



Chiton porosus. Burrow, " Elements of Conchology," 189. pi. 28, f. 1. Acan- 

 thochites porosus, Man. Conch. (1), xv, 36, pi. 3, f. 57-62 ; P. Mai. S., ii. 

 193. Chiton monticularis, Q. & G.. Voy. Astrol., iii, 406. pi. 73, f. 30-35. 

 C. Leachi, Blainv., Diet. Sci. Nat., xxxvi. 554. ? Cryptoplax depressus. 

 Blainv., I.e., xii, 124. ? Cryptoconchus Stewartianus, Rochebr., Bull. Soc. 

 Philom. Paris, 1881-82, 194. C. zealandicus, Quoy : Mutton, T.N.Z.I.. 

 iv, 183, not Q. & G. C. porosus. Burrow: Plate. Zool. Jahrb., v. 319 ; 

 Wissel, op. cit., xx, 618 (anatomy). 



Shell elongated, all but a linear dorsal area of each valve covered 

 by the integument continued upward from the girdle, but in the dried 

 state showing through it the posterior outline of the valves ; colour 

 olive. Head valve with a minute circular exposed apex, centre longi- 

 tudinally grooved, a few concentric flat ridges around it, cut up more 

 or less into flat granules. Intermediate valves with the tegmentum 

 reduced to a narrow flat ledge, drawn out to a long and fine point 

 anteriorly ; pleural areas consisting of elongate narrow triangular and 

 flatly nodulous ridges, terminating at the middle of the jugum. The 

 posterior valve shows a similar sculpture to that of the central valves, 

 but it is very short and wedge-shaped. Girdle naked, smooth, leathery ; 

 bearing a series of prominent tubercles, each with a tuft of short 



