Bnrtiea.'] PELECYPODA 1017 



by supporting radial septa ; hinge-plate reflexed over the beaks, closely 

 applied. 



Distribution. Similar to that of Pholadidea: also Australia. 



Fossil in the Tertiary. 



1. Barnea similis, Gray, 1835. Plate (51, figs. 11, a. 



Pholas similis, Gray, Yate N.Z., 309 ; Conch. Icon., xviii, 1872, f. 10 ; Grit. 

 List, 40. B. similis, Gray, Dieff. N.Z., 254 ; C.M.M., 59 ; Mutton, 

 J. cle Conch., xxvi, 43 ; M.N.Z.M., 132 ; P.L.S. N.S.W., ix, 512 ; Index, 

 88. Pholas aniipodum, Philippi, Zeitschr. f. Malak., iv. 1847. 71. 



Shell fairly large, elongate, acute in front, tapering behind, fairly 

 solid but fragile, very inequilateral, light brown, with concentric 

 lamin?e and anterior ribs and spines. Beaks hidden, a little behind 

 the anterior fourth of the length. Anterior end with a very wide 

 oblique gape, which is not closed in the adult, sharply angled, the 

 dorsal margin lightly convex, descending, concave and very oblique 

 towards the basal margin, which is straight ; posterior end late- 

 rally compressed, lightly gaping, narrowly rounded. Protoplax large, 

 lanceolate, with a median groove and divaricating striae. Mesoplax 

 wanting. Sculpture consisting of somewhat irregularly spaced, sharply 

 raised lamellae, more distant towards the lower and posterior parts of 

 the valves, crossed at the anterior third with sharp radial riblets. 

 widest apart mesially, raised to sharply rounded trigonal spines. 

 Epidermis thin, yellowish-brown, extending beyond the margins of 

 the valves. Colour light brown, white where the epidermis is lost. 

 Interior white, with concentric ribs posteriorly, and radial grooves on 

 the anterior part. Margins smooth, the anterior parts with spines on 

 the outside. Hinge-plate reflected as a white callus over the urnbones 

 and spread as far as the protoplax reaches, the reflexion free anteriorly ; 

 left valve with a tooth-like projection, a little excavated in front, 

 which serves as resilifer for the small resiliurn ; right valve with the 

 resilifer forming a stout, short projection, narrowly hollowed behind ; 

 a long slender apophysis descending from the umbonal cavity. 

 Ligament represented by transverse muscles extending from one 

 valve to the other underneath the protoplax. Adductor-scars very 

 unequal ; the anterior at the angle of the valves, small ; the posterior 

 dorsal, a little behind the middle, elongated, and fairly large. Pallial 

 sinus deep and broad, extending to the radial grooves, broadly convex 

 in front. 



Length, 68 mm. ; height, 22 mm. ; diameter, 22 mm. 



Type in the British Museum. 



Hob. Common in the North Island, rarer in the South ; burrow- 

 ing in soft rock, clay, peat, &c., between tide-marks. 



Maori. Patiotio (teste Captain Bollons). 



Fossil in the Pliocene. 



