Tonicia.] AMPHINEURA. 43 



Anterior valve with 4 low and smooth ridges with serrated margins, 

 corresponding with the slits, anterior margin with the same number 

 of slightly projecting lobes, posterior margin a little concave ; sculpture 

 between the riblets consisting of deeply engraved grooves and punc- 

 tures, leaving numerous wedge-shaped smooth patches of various 

 size ; the whole surface dotted with minute eyes. Of the intermediate 

 valves, the first is notably larger than the following 5, all are sinuated 

 on the latero-anterior sides and narrowed, convex in front and pro- 

 minently beaked behind ; dorsal area V-shaped, smooth, microscopic- 

 ally transversely finely striate ; pleural tracts with a few narrow 

 longitudinal and divergent serrated grooves ; lateral areas not raised, 

 with an anterior obtuse diagonal ridge, sculpture similar to that of the 

 head valve ; the small reddish eyes scattered over the whole surface. 

 Posterior valve with a V-shaped dorsal area, its sides serrated, mucro 

 at about the posterior fourth, posterior slope moderately concave, 

 posterior margin slightly lobed, the lobes corresponding with the 

 slits, sculpture beautifully wedge-shaped, with the postero-lateral ridges 

 corresponding with the anterior slits ; the whole surface covered with 

 minute eyes. Girdle moderately broad, leathery, yellowish, almost 

 naked, with very few silvery fine hairs near the margin. Colour a 

 dirty-white ; anterior valve with the riblets reddish- white, the grooves 

 and punctures rusty ; intermediate valves with the central area light 

 olive, bordered by white, ornamented with very fine longitudinal 

 reddish lines ; grooves on the pleural and lateral areas rusty, a few 

 light-blue spots scattered over the areas ; posterior valve having 

 the central area coloured as the intermediate valves, the grooves rusty, 

 the cuneiform nodules on the pleural tracts light blue ; white, with 

 a few blue spots, posteriorly. Interior greenish-white, without any 

 strong callosity. Anterior valve with 4 slits, the 2 central ones broader ; 

 intermediate valves with 1 slit on each side, and posterior valve with 7 

 inequidistant slits ; all teeth of the first 7 valves finely pectinated and 

 sharp, but those of the tail valve are stout, deeply grooved, rather 

 blunt-edged ; all insertion plates are high ; sinus flat, finely denticu- 

 late ; sutural laminae angularly produced, rather thin ; valve-callus 

 not much raised. 



Length, 22 mm. ; breadth, 11 mm. (dry specimen). Divergence, 78. 

 Animal with the gills extending nearly the whole length of the foot. 



Type in my collection. 



Hab. Bay of Islands (J. C. Anderson). 



Remarks. This shell is distinguished by its peculiar cuneiform 

 sculpture from all the other species of the genus known to me. A 

 curious feature of this species are the minute punctures scattered over 

 the whole surface of all valves, not confined to the lateral areas only 

 on the intermediate valves. I took them for eyes, but I may be 

 wrong. I have only one specimen, and it is highly desirable that 

 more examples should be obtained and carefully examined. 



