150 THE VOYAGE OF H.M.S. CHALLENGER. 



This species is rather raore ventricose than Dosinia scalaris of Menke, in this respect 

 asreeinsr better with Dosinia juvenis, Chemnitz. The concentric rido-es are thickened, 

 with acute edges, upon the central portion of the valves, and separated by deeper 

 sulci than in the two above mentioned species. At the sides, as in this form, 

 they are lamellar and more erect. The broad streak in the interior of the valves, 

 radiating from behind the umbones. is not purple, but dark olive-brown, and is not 

 present in all examples. In some specimens of Dosinia juvenis a similar style of paint- 

 ing is met with. 



With regard to form, this species approaches nearer to Dosinia scalaris than Dosinia 

 juvenis, which is higher in proportion to the length, and does not, so far as I am aware, 

 attain such large dimensions as Dosinia deshayesii, w^hich are as follows : — length 50 mm., 

 height 45, diameter 26. The area is deeper than in Dosinia scalaris, and defined by 

 angular edges, particularly noticeable in the left valve, resembling Dosinia juvenis. On 

 the contrary, the pallial line is nearer the margin in this species and Dosinia scalaris 

 than in Dosinia juvenis. 



Adams describes the colour as "rufescente, albo variegata." This description does 

 not give a sufficient idea of the painting of this shell, which may be said to be reddish- 

 brown varied with four more or less distinct white rays, one down the posterior dorsal 

 slope, one bordering the lunular margin, and the two others upon the centre of the 

 valves. These rays in some specimens are almost obliterated or confused with the 

 ground colour of the shell, and at the two ends of the valves there are frequently more or 

 less angular markings and oblique lines upon the pale rays. The lunule is ^particularly 

 wide, certainly wider than in Dosinia scalaris, if not deeper. In conclusion, I may 

 observe that all these three species are very closely related, and by some might be 

 regarded as variations of one and the same species, but if Dosinia .scalaris be 

 retained distinct from Dosinia juvenis, we must then admit the validity of the 

 present form. 



Dosinia circinaria, Deshayes (PI. I. figs. 2-2f ). 



Dosinia circinaria, Deshayes, Cat. Conchif. Brit.. j\Ius., p. 9. 

 Dosinia circinaria, Romer, Monog. Dosinia, p. 19. 



Habitat. — Port Jackson, New South Wales, in 6 to 7 fathoms. 



The localit)- of this species has not hitherto been known. The tip of the umbones 

 appears to be generally stained with a pale brownish colour, a feature not referred to by 

 Deshayes, who also does not give any dimensions. The type which is now figured is 

 28 mm. long, 27 high, and 16 in diameter. 



