166 MYTILIDA. 
Genus, SOLENELLA—Sowerby. 
Shell oval, gaping and truncated benind; valves concentrically 
striated and covered with a brownish-green epidermis; hinge line 
straight, with small comb-like teeth. 
South America. New Zealand and Kerguelen’s Land only. 
S. australis, Quoy and Gaimard, Lc., iti., p. 471, pl. 78, f. 5-10 ; 
Reeve, Conch. 1c:,°f. 4; Voy. Erebus *and* Lerror, Moll., pl. 2, f. 13% 
Netlo cumingit, A. Adams, P.Z.S., 1852, p. 93; Chenu, f. 914. Trans- 
versely oblong, rounded in front ; produced and waved behind ; pos- 
terior dorsal margin slightly concave ; posterior end truncated, emargi- 
nated ; ventral margin straight; valves with rather distant (about forty to 
an inch) concentric, rather elevated striz ; pale. olive-green, interior 
greyish-white. 
Height, °5; length, 11. 
Wellington Harbour. Stewart Island. 
The specimen from Stewart Island has the posterior margin less 
sinuated. 
ORDER—HETEROMYA. 
Muscular scars double, unequal, sometimes becoming monomyary 
in the adult. Shells generally equivalve, ligament external, no lateral 
teeth. 
FAMILY—MYTILID/. 
Labial palps elongate, pointed, free. Mantle margins free, or united 
behind to form a more or less complete anal tube. Gills two on each 
side, nearly equal, elongated, dependent, united behind to each other 
and to the mantle. Foot narrow, strap-shaped, furnished with a byssal 
groove. Shell equivalve, oval or elongated, closed ; umbones anterior ; 
epidermis thick and dark, often filamentose ; ligament internal, sub- 
marginal, very long; hinge edentulous; pallial line simple; anterior 
muscular impression small and narrow ; posterior large, obscure. 
Sub-Family—Mytiline. 
Hinder part of mantle only slightly produced ; anterior adductor 
muscle small. 
Genus, MYTILUS—Linneus. 
Mantle freely open; ventral margin simple; branchial furnished 
with pinnated fringes; anal opening plain and sessile. Shell wedge- 
shaped, rounded behind; umbones terminal, pointed; hinge teeth 
minute or obsolete ; pedal impressions two in each valve, small, simple, 
close to the adductors. 
M. magellanicus, Lamark, 1.¢., vii., p. 37; Reeve, Conch. Lc., f. 
22; Chenu, f. 746. Oblong, sub-trigonal, angled, uncinate, with thick 
