232 APPENDIX. No. V. 



My a truncata, Lion. 



Hab. Discovery Bay, 5 and 25 fms. {Hart and Feilden) ; 

 Dobbin Bay, 30 fms. (Hart). 



All the specimens from these localities have the posterior 

 marginal slopes directed inwards or towards the base of the 

 shell, which peculiarity is characteristic of the variety ud- 

 devalensis. One shell is remarkable on account of the 

 abruptness of the truncation and its narrowness, the width 

 being only 6 millims. more than the length (30 millims.) 



Saxicava arctica, Linn. 



Hab. Discovery Bay, 5 fms. (Feilden) ; Franklin Pierce 

 Bay (Hart and Feilden) ; Dobbin Bay, 30 fms. {Hart). 



Some specimens from Franklin Pierce Bay are remarkable 

 on account of their great solidity, the depth and distinctness 

 of the muscular scars, and the purplish brown colour which 

 stains both the inside and exterior of the valves. 



Modiolaria laevigata, Gray. 



Hab. Franklin Pierce Bay, 15 fms. {Feilden and Hart). 



This species is considered by some authors a variety of the 

 British M. discors. There are, however, certain differences 

 in form, colour, and sculpture which appear to me sufficient 

 to distinguish the two species. The present is a larger 

 species, transversely more elongate and proportionally nar- 

 rower, the difference in width of the anterior and posterior 

 ends being less marked. The striae on the hinder area, in 

 adult specimens, are distinct only towards the umbones, and 

 gradually become obsolete towards the margin of the valves, 

 which, on this account, are smooth and not denticulated 

 within as in discors. The epidermis of laevigata is brown on 

 the greater portion of the shell, becoming pale olive or 

 brownish green towards the umbones. 



