165 



Interior of Shell. — Porcelaneous, with raised riblets on 

 posterior part of valve, sinus shallow and wavy, sutural 

 laminae very short. 



Girdle. — Covered with irregular appressed spinelets, 

 coarser towards the outer margin. In curled specimens these 

 spines are erect, creamy-white with red spashes. 



Measurement. — 10 x 5 mm. 



Hab. — Dredged by Dr. Verco in Spencer Gulf. One 

 specimen was found by the writer on the north-west coast 

 of Tasmania, and another from the same locality is in the 

 possession of Mr. Basset Hull. 



Remarks. — I have had considerable difficulty in deter- 

 mining the genus of this shell. It has pectinated teeth and 

 eyes like Tonicia, but the girdle is not leathery, nor are the 

 valves so polished. It may be a Chceto pleura. The descrip- 

 tion is repeated, as the dredged South Australian specimens 

 differ from the account given by Dr. Torr in the Proc. Roy. 

 Soc, Tasmania. No eye-dots can be seen in the Tasmanian 

 specimen. 



56. Lepidopleurus pelagicus, sp nov. PI. v., figs 2a-f. 



General Appearance. — Ovate, decidedly arched and 

 strongly carinated. Side slopes straight. The shell gradually 

 tapers towards the tail valve. The valves overlap the girdle. 

 Colour. — Uniform, pale sulphur-yellow; the girdle has a 

 slightly deeper shade, almost brown when dried. 



Anterior Valve. — Broader than the median valves. It 

 has three or four concentric grooves or growth markings 

 parallel to the girdle, crossed by a number of minute stria- 

 tions converging towards the apex. The interior is pearly- 

 white. No dentition nor sutural laminae. The posterior edge 

 of the valve is serrated. 



Median Valve. — The lateral area is gradually elevated 

 above the central area. The whole of the valve is covered 

 with minute tubercles in longitudinal rows in the dorsal and 

 pleural areas. Under the microscope, these appear like 

 strings of beads. The rows are transverse in the lateral areas. 

 The sutural plates are diminutive and semi-transparent, the 

 sinus very broad. The posterior edge of the valve is ser- 

 rated. Interior pearly and semi-transparent, the striations 

 of the tegmentum distinctly shows through. 



Posterior Valve. — Mucro median elevated, with concave 

 slope to girdle. Pustulose lirae converge to the mucro. 

 Sutural plates delicately diminutive. 



Girdle. — Leathery and spiny to the unaided eye. Under 

 H-in. lens it is covered with minute specules. 



