1881.] THE SURVEY OF H. M.S. 'alert.' 39 



acute. Lunule narrow. Ligamental area lanceolate, twice as long 

 as the ligament. Hinge with two teeth in each valve, whereof tlie 

 anterior in the right valve and the posterior in the left are bifid. 

 Anterior scar narrow, elongate, running some way from the upper 

 front margin downwards ; posterior scar broader, roundly ovate. 

 Pallial line simple, joining the front scar at its upper end. Interior 

 of valves exhibiting an irregular corrugation or punctation. Width 

 9i millims., length 8, thickness 3i. 



Hab. Station 5. 



Tliis pretty species is very different from most others of the genus 

 in being sculptured with raised lamellae, 



Mactra (Mulinia) levicardo, sp. n. (Plate V. figs. 2-2 b.) 



Shell ovate, subtrigonal, inequilateral, livid from the centre of the 

 valves to the umbones, elsewhere white, covered with a greyish-olive 

 epidermis. Valves moderately convex, with a faint ridge or angula- 

 tion from the umbo to the hinder extremity, which is very 

 slightly angulated, and witli a shallow depression nearer the dorsal 

 line, marked by a "wrinkling of the epidermis. Interior white. 

 The sculpture consists of concentric stripe, very fine near the apex, 

 and rather coarse towards the outer margin. Umbones small, acute, 

 not far apart, situated a little anteriorly. Hinge remarkable on 

 account of the small size of the cartilage-pit ; and the whole con- 

 struction of the hinge is slight. Pallial sinus rather deep, but not 

 acute. Diam. 56 millims., length 44, thickness 22. 



Hub. Cockle Cove, 7 fathoms., mud. 



M. edulis of King appears to be the nearest ally of this species, 

 which differs especially in having a much smaller cartilage-pit, a less 

 deep pallial sinus. The form also is more transverse and the dorsal 

 slopes less arcuate, thus giving a more triangular appearance to the 

 outline. 



NucuLA pisuM, var. 



Hab. Station 2. 



A. single specimen of this species is of a rather narrower and more 

 ttiangular form than normal examples. 



Leda lugubris, a. Adams. 



Hab. Station 2; and Wolsey anchorage, 17 fathoms, mud and 

 gravel. 



Malletia magellanica. Smith, (Plate V. figs. 3, 3 a.) 



Hab. Station 3, Mayne Harbour, 9 fathoms, greenish mud ; and 

 Cockle Cove, 2-32 fathoms, mud. 



The typical specimens of this species were collected somewhat 

 south of the above localities at Otter Island. One of those just 

 received is a very fine example, being 38 millims. broad, with a 

 length of 20 ; and the beaked end is remarkably acute. 



