928 PELECYPODA. [EuJamellibranchia. 



3. Lassea scalaris, Philippi, 1847. Plate 53, fig. 15. 



Poronia scalaris, Phil., Zeitschr. f. Malak., iv, 1847, 72 ; Angas, P.Z.S., 

 1867, 926. Lascea scalaris, Phil. : Hedley, Mem. A.M., iv, pt. 5, 32 L 

 Poronia Parreyssi, Philippi, op. cit., 73. P. purpurala, Phil., op. cit., 

 73. P. rugosa, Recluz, J. de Conch., iv, 1853, 50, pi. 2, f. 4, 5. P. aus- 

 tralis, Souverbie, J. de Conch., xi, 1863, 287, pi. 12, f. 8 ; Angas, P.Z.S., 

 1867, 926. Kellia balaustina, Gould, P. Bost. S.N.H., viii, 1861, 34. 



Shell small, oval, oblique, inflated, inequilateral, concentrically 

 striated, yellowish-brown stained with pink. Beaks prominent, con- 

 vex, incurved, somewhat excavated in front, pointed. Anterior end 

 produced, much longer than the posterior, narrowly convex at the 

 middle, the dorsal margin rounded and gently sloping ; posterior end 

 semicircular, basal margin lightly rounded. Sculpture consisting of 

 concentric striae, sometimes rather coarse and fine wrinkles and 

 punctures. Colour yellowish-brown with pink at the dorsal parts. 

 Interior whitish, the hinge-margin and anterior end pink, smooth. 

 Margins thin, smooth, and sharp. Hinge-plate well developed, angular, 

 right valve with a small triangular cardinal, 2 very short triangularly 

 raised anterior laterals, and 2 elongated curved posterior lamellae, 

 the lower one stronger and raised at the end ; left valve with a minute 

 cardinal, 1 tubercular small anterior lateral, and 1 elongated posterior 

 lateral, above which there is usually a subparallel fine lamella. 

 Resilium large, extending from the centre towards the posterior lower 

 part of the hinge-plate. Adductor-scars distinct, the anterior larger, 

 oval, the posterior smaller, roundish. Pallial line entire. 



Diameter Ant. -post., 7mm.; dorso-ventral, 5-5 mm. : thick- 

 ness, 4-5 mm. 



Hal). Taumaki Island, in 10 fathoms (Captain Bollons) ; Stewart 

 Island. Also Australia, Tasmania, &c. 



Genus 5. MYLLITA, d'Orbigny and Recluz, 1850. 



Myllita, d'Orb. & Reel., J. de Conch., i, 1850, 292. Type: .Erycina Des- 

 hayesii, Recluz. Mylilta, Kobelt, 1878. Pythina, T. -Woods, Button. 



Shell equivalve, solid, surface punctate or sagrinate, with con- 

 centric, radial, or divaricate sculpture ; ligament external, obsolete, 

 amphidetic ; resiliiim strong, internal, seated in a conspicuous sulcus 

 below the lower posterior lamina, the mesial portion with a calcareous 

 coating ; valves with a small anterior and posterior dorsal gape, but 

 closed ventrally ; hinge with a single left anterior and posterior lamina 

 and a single left cardinal ; right valve with a cardinal and double 

 anterior and posterior laminae, the cardinals often bifurcate ; mantle 

 completely open below between the adductors, and probably covering 

 more or less of the exterior of the valves ; pallial line simple, with 

 large adductor-scars ; foot strong, with a conspicuous byssal sulcus ; 

 the young incubated in the generative or peripheral atrium, small, 

 vitreous, and numerous. (Dall.) 



Distribution. Australia, Tasmania, New Zealand. 



