REPORT ON THE LAMELLIBRANCHIATA. 273 



A uiiml)er of dead valves, all that was obtained, undoulttedly Itelong to this species as 

 figured by Reeve. There are iu the British Museum also other specimens from the coast of 

 Australia, and another series from Jamaica appears all but identical, but the dorsal angle 

 in these specimens is more prominent, the sinuatiou in the outline behind it is more 

 marked, and the radiating strise are continued feebly right to the anterior end, whilst iu 

 the Australian examples there is a slight interruption of them near that extremity. 



Mytilus hii'sutus, Lamarck. 



MijtiluK liirgutus. Lamarck, Reeve, Concli. Icon., vol. x. pi. Hi. fig. 8. 

 Mytilus hirsutas, Dunker, Ind. Moll. Japon., p. 222. 



Mytilus (Aulacomya) hirsutus, Angas, Proc. Zool. Soe. Lond., 1865, p. 6-52. 

 Mytilus (Aiilacoiii ya) hirsutus, Angas, ojh cif., 1867, p. 928. 



Habitat. — Port Jackson, Sydney, in 6 to 15 fathoms. 



This species ranges from South Australia, also along the east coast, and as far north 

 as China and Japan. It is also said by Angas to have been found at New Zealand, but 

 this has not .since been confirmed. 



Mytilus mevidionalis, n. sp. (PL XVI. figs. 3-3a). 



Testa compressa, subovata, superne subacuminata, ad apicem obtu.sa, alta, allja, striis 

 increment! insculpta, prope umbones oljsolete radiatim costata. Margo dorsi utrinque 

 valde decli^ds, antice elongatus, postice brevior, minus obliquus. Cardo edentulus. 

 Ligamentum magnum, subinternum, in fossa elongata, haud profunda, latiuscula situm. 

 Pagina interna superne callosa, inferne tenuior, radiatim minute substriata, ad marginem 

 acuta, simplex. 



This species is much flattened, higher than long, irregularly ovate, and somewhat 

 acuminate above. It is white, glossy, and striated ])y concentric lines of growth, some 

 of which are more strongly marked than others. It is also sculjiturcd with a few feeble 

 ridges which radiate from tlie beaks. The dorsal margins are almost straight but unequal, 

 the anterior being the longer and rather more sloping than the posterior. The uml)0 in 

 both the valves under examination is prominent, and terminates iu an ol)tuse apex, 

 surrounded as it were b)^ a thickened collar. In front of it iu the right valve there is a 

 narrow but very deep lunular excavation, and l)ehind, in a broad shallow elongate groove 

 on the toothless hinge-plate, is placed the ligament, which may be described as subexternal, 

 as it would be slightly visible when the valves were closed. The interior is thickened at 

 the upper part with a minutely rugose, dull, shelly deposit, becoming thinner as the lower 

 margin is approached, and displaying a faint radiate sul)striation. The pallial line and 



muscular scars are indistinct. 



(zool. chall. EXP. — PART xx.KV. — 1885.) Mm 35 



