40 ACANTHOCHITES-LOBOPLAX. 



Conch. Icon., t. 10, f. 56 (April, lS47).Phacellopleura porphyre- 

 tica CPU. MS. 



This species has a wide range of variation in coloring, in the 

 angle of divergence of the valves, and to a less extent in the contours 

 of the valves. 



A. COSTATUS Adams & Angas. PI. 3, fig. 74. 



Shell elongated ; valves carinated, angularly heart-shaped, gran- 

 ulated, pale brown. Lateral areas separated from the dorsal areas 

 by a prominent rib ; dorsal areas smooth and whitish in the middle. 



Girdle beset with short, white, evanescent spicules, and having 

 bunches of long white spicules. 



Length 18, breadth 7 mill. (A. & A.) 



Port Jackson, New South Wales, Australia. 



Aeanthochites costatus A. & A., P. Z. S. 1864, p. 194. ANGAS, I. 

 c. 1867, p. 224. Macandrellus costatus DALL, Proc. U. S. Nat. Mus. 

 i, p. 81, f. 40 (dentition). Chiton (Macandrellus} costatus E. A. 

 SMITH, Zool. Coll. ' Alert,' p. 83, t. 6, f. F. 



Smith gives the following notes on the specimen collected by 

 Coppinger: " The single specimen before me, preserved inspirit, 

 shows the girdle to be of a pale buff color, 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 substriated flattened 

 ridge, on each side of which the surface is granulated or rather 

 squamose, the scales being flat, imbricating, rather large, and dis- 

 posed in rather regular series. The lateral areas are well defined by 

 a raised keel. The front valve has five radiating costse, 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 indicated. The single notch on each side the inter- 

 mediate valves is also very slight. The posterior valve has a raised, 

 somewhat excentric 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." 



A. TRIDACNA Rochebrune. 



Shell ovate-elongate, white, shining. Anterior valve rounded, 

 strongly 7-lirate radially, the lirse thick, rounded, scaly, elevated in 

 front. Intermediate valves broadly triangular, the central areas 



