132 



DESCRIPTION OF A NEW RECENT PHOLADOMYA 

 {PH. TASMANICA). 



By C. Hkdlet and W. L. May. 



Read 17th April, 1914. 



The antiquity of this genus and the small number of survivors lend 

 an interest to any new member of Pholadomya, especially when it 

 appears in a fresh region. 



This southern form is readily distinguished from the half-dozen 

 recent species by the remarkable shortness of the anterior side. 

 Judging from literature, it approaches nearest to Ph. arata, Verrill 

 and Smith (Trans. Conn. Acad., vol. v, p. 567, pi. Iviii, fig. 3, 1882), 

 from the North-Eastern United States, and Ph. africana, Locard (Zool. 

 Travailleur & Talisman, Moll., vol. ii, p. 167, pl. vii, figs. 42-5, 1898), 

 from tlie jS^orth-West of Africa. These were included in a genus 

 Panacea, proposed by Dr. W. H. Dall (Nautilus, vol. xviii, p. 143, 

 1905). 



In Torres Strait occurs Pholadomya haddoni, Melvill & Standen 

 (Journ. Linn. Soc.,Zool., 1899, p. 202, pl. xi, fig. 22), which is perhaps 

 better ranked as a genus apart, Parilimya. The Australian Tertiary 

 Ph. australica, Tate (Journ. Hoy. Soc. N.S. Wales, vol. xxii, p. 187, 

 pl. xii, fig. 2, 1893), is quite unlike the recent Tasmanian shell. 

 Ph. arenosa, Hedley (Proc. Linn. Soc. N.S. Wales, vol. xxix, p. 197, 

 pl. ix, figs. 26-7, l'904; vol. xxxi, p. 464, 1906), doubtfully referred 

 to this genus, is smaller, shorter, and more equilateral than 

 Ph. tasmatiica. 



Pholadomya tasmanica, n.sp. 



Shell faintly nacreous, tliin, fragile, semi-translucent, sub-trigonal, 

 inflated, very inequilateral, the posterior end being four times the 

 length of the anterior, posteriorly rounded, anteriorly truncate, dorsal 

 and ventral margins nearly straight. Colour buff. Sculptured by 

 narrow ridges radiating from the umbo, parted by broad shallow 

 furrows, growing closer and weaker posteriorly, in number eighteen 

 on the shell figured, but about thirty on a fragment of a larger 

 specimen. Anterior side with a single broad radial fold. Entire 

 surface roughened with fine dense grains, usually packed in lines of 

 growth. Umbo unbroken, elevated, incurved, directed anteriorly. 

 A groove on the anterior hinge-margin suggests that the edge of the 

 unseen left valve is here received as a lateral tooth. Chondrophore 

 narrow, posterior to the umbo. Interior very glossy ; adductor scars 

 distinct, low down ; pallial sinus well developed, the apex of its 



