40 ACANTHOCHITLS-LOIiori.AX. 



Conch. Icon., t. 10, f. 56 (April, 1847 >. rii<ir<llopleura 



MS, 



Tliis 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. 



-TATU8 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. 



-th 18, breadth 7 mill. (A. & A.) 



Port Jack*on, Xeiv South Wales, Australia. 



.1 v 0A&M costatus A. & A., P. Z. S. 1864, p. 194. ANGAS, /. 

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

 i. p. 81, f. 40 (dentition). Chitir Macandrellus) costatu* E. A. 

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



Smith gives the following notes on the specimen collected by 

 i nircr: " 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 ra^ed, 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 costie, and 

 apparently the same number of slits in the thin lamina of insertion 

 <>f whirh the three central are quite distinct and the two outer ones 

 only trebly indicated. The single notch on each side the inter- 

 mediate valves is also very slight. The posterior valve has a rai ><!. 

 somewhat excentric and pointed mucro, from which six more or less 

 di-tinct radiating ridges descend to the margin, beneath which the 

 lamina of insertion is scalloped by a similar number of note-In >." 



A. TR1DACNA Rochchnilir. 



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

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

 front. I nt rmediate valves broadly triangular, the central air:is 



