220 ACANTHOPLEURA. 



ulation of the valves, and in interior coloring, A. spinosa is very 

 closely allied to A. spiniger Sowb., from which the occasional radsi- 

 oid slitting, and the feeble denticulation of the sinus in the second 

 valve, separate it specifically. Dr. Carpenter's subgenus Francisia 

 included A. spinosa only. 



A. SPINOSA Bruguiere. PL 45, figs. 80-87. 



Shell oblong, depressed, smoothish and black ; girdle wide, covered 

 with long, brittle black spines. 



The valves are smooth except for growth-lines on central areas 

 and some inconspicuous radial wrinkling or obscure granulation on 

 the very feebly defined, small, lateral areas. End valves somewhat 

 rugose-granose radially, the mucro posterior. 



Inside purple-red in the middle, white on the sutural-plates and 

 the region of the lateral slit-rays. Sinus of second valve cut into 

 delicate square denticles by short linear slits, but in the other valves 

 the denticulation is obsolete. Slits in anterior valve 15, central 

 valves 1 or 2, posterior valve 10 ; teeth of end-valves long, grooved 

 outside and crenulated at the edges, the posterior teeth vertical; 

 teeth of intermediate- valves triangular, the posterior tooth, when 

 present, very small. Sutural plates long, separated by a deep sinus 

 broader than the plates. 



Girdle wide, rusty, beset with long brittle black spines (fig. 86.) 



Length 50, breadth 28 mill. 



Albany Island, Cape York, North Australia (Challenger.) 



Chiton spinosus BRUGUIERE, Journal d'Histoire Naturelle, i, p. 

 25, t. 2, f. 1, 2 (1792). LAMARCK, An. s. Vert, vi, p. 321 (1819). 

 SOWERBY, Genera of Shells, Cephala, Chiton, f. 1 ; and Conch. 

 Illustr. p. 1, f. 151. REEVE, Conch. Syst. ii, p. 12, t. 134, f. 151 ; 

 and Conch. Icon., t. 9, f. 51. Francisia spinosa CARPENTER MS. 

 Maugeria spinosus GRAY, Guide Moll, B. M., p. 184. Francisia 

 spinosa HADDON, Challenger Rep., p. 30. 



The radsioid slitting of some of the valves and the lack of distinct 

 areas and valve sculpture, well distinguish this species. The slits 

 are really very short, but are continued on the outside as grooves, 

 up to the eaves. The eyes appear as minute amber colored beads, 

 sparsely scattered down the forward half of the lateral areas, but 

 scarcely arranged in rows. Poorly preserved or very old specimens 

 show their pits only. 



