MoM.CSCA. 83 



1 15. Chiton ( Macandrellus ) costatus. (Plate VI. fig. F.) 



Acanthoehites custatus, II. Attains 8f Angas, Proc. Zool. Soc. 1864, 



p. 11)4 ; Angas, I. c. 1867, p. 224. 

 Macandrellus costatus, Doll, Bull. U.S. Nat. Mas. i. p. 81, fig. 40 



(dentition). 



Hob. Port Jackson {Angas and Coppinger). 



The single specimen before me, preserved in spirit, shows the 

 girdle to be of a pale buff colour, thick, fleshy, the outer margin 

 being delicately ciliated with a minute fringe of white spicules. 

 The tufts of spicules are seven in number along each side, and four 

 surrounding the front valve. The middle of the central valves is 

 occupied by a raised, transversely substituted flattened ridge, on each 

 side of which the surface is granulated or rather squamose, the 

 scales being flat, imbricating, rather large, and disposed in rather 

 regular series. The lateral areas are well defined by a raised keel. 

 The front valve has five radiating costa?, and apparently the same 

 number of slits in the thin lamina of insertion, of which the three 

 central are quite distinct, and the two outer ones only feebly indi- 

 cated. The single notch on each side the intermediate valves is 

 also very slight. The posterior valve has a raised, somewhat ex- 

 centric and pointed mucro, from which six more or less distinct 

 radiating ridges descend to the margin, beneath which the lamina 

 of insertion is scalloped by a similar number of notches. 



116. Chiton (Acanthochiton ) asbestoides. (Plate VI. fig. G.) 



Shell small, greyish brown, with a pale line on each side the 

 middle of the central valves, slightly converging behind, leaving a 

 dark wedge-shaped space between them. Surface covered with a 

 coarsish granulation, the granules being somewhat flattened, and 

 those at the vertex of the central valves rather smaller than tho 

 rest. The lateral areas are not defined in these valves ; the posterior 

 curved margins are produced in the middle, at times almost forming 

 a right angle ; their insertion-plates are large, thin, produced ante- 

 riorly, with a very slight notch quite close to the hinder margin on 

 each side ; the sinus between them in front is deep and arcuate. 

 The "first valve has a straighter posterior margin than the succeed- 

 ing ones, and a semicircular outline in front ; the lamina of inser- 

 tion is rather deep, thin, feebly striated exteriorly, and interrupted 

 by five very small subequidistant notches. The last valve is con- 

 spicuously small, transversely subovate, depressed-conical, with a 

 nearly central mucro ; insertion-plate very large, laterally produced, 

 with only two notches behind. Interior of the valves bluish. 

 Mantle very minutely spinulose, bearing very conspicuous compact 

 tufts of silky spicules along the sides, not at all unlike in their fibrous 

 texture that of asbestos. Length 15 millim., width of the broadest 

 central valve 5g. 



Hah. Flinders Island, Bass's Straits (Joseph Milligan); Port 

 Molle, Queensland {Coppinger). 



g2 



