84 PROCEEDINGS OF THE ACADEMY OF [1894. 



pinnately corrugated, the lower margin of the tegmentum feebly 

 angulated by them. Posterior valve having a large, irregularly 

 rounded tegmentum, ribbed in front, granulated behind; mucro at 

 the posterior fourth of tegmoitnm, decurved and hooked, the slope be- 

 hind it concave. 



Interior white, with bluish macuhe at sinus and bases of the sutural 

 laminiw Anterior valve with five, intermediate valves 1-1 slits; 

 posterior valve having the posterior insertion- plate flaring backward 

 and outward, with one strong slit on each side and several (two or 

 three) between them. Sinus rather wide. 



Girdle narrow, densely clothed witli minute spicules, and having 

 rather large bunches of vei'y short white spicules at the sutures. 



Length 26, breadth 8 mm. (dried specimen). 



Habitat: South Australia (E. H. Matthews !) 



The sculpture of this species is extremely peculiar, and totally dif- 

 ferent from that of any previously known member of the family 

 Acaiithochitidce. The coloring is also markedly distinct. The type 

 was sent me by Mr. W. T. Bednall of Adelaide, South Australia, 

 who suggested the specific name employed above. Although techni- 

 cally a Notoplax in its multifissate tail valve, this species is very un- 

 like A. speciosus, the type of that group. 



Acantliochites (Notoplax I) variabilis. 



IhDilcva variabilis H. Ad. :iiul C. F. Aug., V. Z. S., 1864, p. 191; Augas, P. 

 Z. S., 1865, p. 188. 



Shell oblong, whitish, variegated with blackish-brown. Valves 

 broad, carinated; dorsal areas longitudinally densely costate, the 

 ribs closely pustulose; lateral areas but slightly elevated, trans- 

 versely undulately costate, the costie closely pustulose. Girdle hav- 

 ing short white corneous S})icules at the margin, and bunches of pale 

 spicules. Length 16, breadth 10 nmi. 



Habitat: Yorke Peninsula, under stones at low water (Angas). 



The above translation of the original description is given for com- 

 parison with that of A. Matthenm. This species is otherwise un- 

 known to me, and may prove to belong to some other group. It is 

 evidently distinct from A. Matthewsi, the proportions of breadth to 

 length in the two being so difterent as to preclude the suspicion of 

 identity which I at first entertained. 



