127 



EAMILY AECAD.E. 



SUB-FAMILY NUCULIN^. 



Genus Nucula. 



synopsis of species. 



Shell smooth, margin not crenulated. iV. titmida. 



Shell concentrically ridged and radially striated, margin 



crenulated. 



Obliquely trigonal, folds thin. N. AtJcinsoni. 



More oblique, folds thick. N. semistriata. 



Trigonal, equilateral. N. Morundiana. 



Shell with fenestrated ornament. N.fenestralis. 



Nucula tumida, Tenison-Woods. PL vi., figs. 6a— 6&. 



Reference. — Proceedings Royal Soc, Tasmania, for 1877, 

 p. iii. 



Shell solid, obliquely trigonal, tumid, truncated posteriorly, 

 slightly produced and rounded anteriorly, wrinkled with con- 

 secutive irregular, flattened folds of growth, increasing in 

 thickness from the umbos to the margin ; margin acute. Hinge 

 teeth diverging progressively in an increasing series, inter- 

 rupted by a narrow deep ligamental pit, which is obliquely 

 produced posteriorly ; the teeth are lanceolate, high, and 

 lamellar, the distal ones smaller ; in the posterior row there 

 are eight, and in the anterior row about thirty. Umbos acute 

 .and sharply incurved ; lunule shallow, but well defined, 

 wrinkled and broadly lanceolate. 



Dimensions. — Length, 21- height, 16; thickness through 

 both valves, 14 millmietres. 



Localities. — Tasmania : Table Cape (locality of the type) 

 .(^Tenison-Woods and B. M. Johnston !). 



Victoria : Muddy Creek, Hamilton (common and large) ; 

 Corio Bay, Greelong ; Schnapper Point, Port Philip. 



South Australia: Grastropod bed, Middle Murravian, near 

 Morgan {B.T.) 



The author of this species states that it is " not unlike 

 the Tasmanian JSI'. Grayii, Sow., but is more tumid and con- 

 spicuously sulcate," distinctions which I confirm. 



Nucula Atkinsoni, R. M. Johmton. PI. iv., fig. 3a— 3c. 



Reference. — JPortlandia Atkinsoni, E. M. Johnston, in Proc. 

 Eoy. Soc, Tasm., vol. for 1880, p. 39. 



Shell small, obliquely trigonal, subdepressed ; the very short 

 posterior slope truncated. Surface of valves concentrically 

 finely ridged ; the ridges increase in size, and frequently 

 anastomose towards the centre and margin, and are traversed 



