t 



ISCHNOCHITON-ISCHNORADSIA. 145 



sculptured with finer longitudinal rib lets, obsolete on the ridge, 

 where they give place to a dense microscopic granulation. The worn 

 apices of the valves are pink in mature shells. End valves sculpt- 

 ured with close radiating riblets, those of the posterior valve irreg- 

 ularly granose ; mucro rather depressed ; posterior slopes of the tail 

 valve depressed and concave. 



Interior light blue-green, with two wide pink rays in each valve, 

 and behind them two olive-brown rays. Sutural plates rounded, 

 whitish or yellowish ; sinus wide, flat, not in the least toothed. 

 Insertion plates having 16-21 slits in the anterior, 2 or 3 in the 

 median, and 17-21 in the posterior valve ; teeth rather thick and 

 stumpy, and a little rugose, but sharp edged. Eaves wide and solid. 

 Girdle (fig. 57) wide, closely covered with conspicuous, convex, 

 pebble-like scales, which toward the outer edge are subcarinated in 

 the middle. 



Length 62, breadth 35 mill. 



Port Jackson, Australia. 



Chiton australis SOWERBY, Mag. of Nat. Hist. (Charlesworth's), 

 June, 1840, p. 290 ; Conch. Icon., f. 46. REEVE, Conch. Icon., t. 2, 

 f. IQ.Lophyrus australis ANGAS, P. Z. S. 1867, p. 221. Lepido- 

 radsia australis CPR., MS. and DALL, Proc. U. S. Nat. Mus. 1878, 

 p. 279, t. 2, f. 19 (dentition) ; p. 333 (branchiae). HADDON, 

 ' Challenger' Rep., Polyplac., p. 19. Chiton (Ischnoradsid) australis 

 SHUTTLW., Bern. Mittheil., 1853, p. 66. C. evanidus SOWERBY, 

 Mag. Nat. Hist, iv, June, 1840, p. 291 ; Conch. Illustr., f. 139. C. 

 metallicus RVE., Conch. Icon., t. 17, f. 104, 1847. 



This species is distinguished from the following by the fine longitu- 

 dinal ribbing of the central areas. The synonymy given above is 

 unquestionable. 



Occasionally one or more of the teeth is cloven into a number of 

 small ones ; the number of teeth varies considerable. 



Dall found the gill rows to extend the whole length of the foot, 

 and to contain forty-seven branchiae in each. Mantle-edge plain, 

 thin ; muzzle plain, semicircular, without a veil. 



I. NOVJEHOLLANDI^E (Gray) Reeve. PL 19, figs. 67, 68, 69. 



Shell oval-oblong, elevated, the dorsal ridge angular, side-slopes 

 nearly straight. Color green, minutely marbled with olive, the 

 lateral areas darker. 

 10 



