68 THE VOYAGE OF H.M.S. CHALLENGER. 



surface is dull, roughish, or minutely subgranulated about the middle, smoother, more 

 shining, and radiately substriated towards the ventral margin. 



Reeve recognised the general outward resemblance of this form to Myodora, and it is 

 to be regretted that he did not, before describing it, examine the hinge. Had he done 

 so he would at once have perceived that it did not corres^jond with that of TJiracia, but 

 in reality was truly Myodoroid. His conjecture that his TJiracia novo-zelandica might 

 possibly be a variety of Thracia australica is confirmed l;)y the fact that it also proves to 

 belong to Myodora, and the locality " New Zealand " has yet to be confirmed, for, so far 

 as at present known with absolute certainty, the species appears to be limited to New 

 South Wales and Queensland. 



Myodora angustata (Angas). 



Alicia angustata, Angas, Proc. Zool. Soc. Lond., 1867, p. 908, pi. xliv. fig. L 

 Habitat. — Port Jackson, Sydney, in 2 to 10 fathoms. 



At present I see no gi-ounds for separating this species and Alicia^ elegantula, Angas, 

 generically. Both species have the left valve smaller than the right, are white, 

 truncated posteriorly, and sculptured microscopically as in all the species of Myodora. 

 The composition of the hinge in both proves to be identical, and the pallial line is 

 sinuated. The more elongate form and the fact of the left valve l^eing rather moi'e 

 convex than in most other species are not in my judgment characters of any importance 

 from a generic point of view. 



Subfamily Thraciin.e. 



Thracia, Leach. 



Thrxicia meridionalis, n. sp. (PI. YI. figs. 4—46). 



Testa paulo iusequilateralis, modice convexa, ovato-oblouga, postice truncata, cariuam 

 obsoletam ab umbonibus ad extremitatem posticam exhiljeus, sordide albida, lineis 

 incrementi rugosis, striisque tenuibus concentrice seulpta,undique minute grano-scobinata; 

 margo dorsi antice valde declivis, aliquanto arcuatus, postice brevior, minus descendens, 

 rectiusculus; margo ventris levis.sime excurvatus, uti'inque parum adscendens. Latus 

 anticum rotundatum, posticum oblique, vix arcuatim tnmcatum. Cardo, cicatrices et 

 lallii sinus fere \\t in TJiracia truncata (Brown). 



This species is of an oblong form, rounded in front and squarely truncated posteriorly, 

 slightly inequilateral, the anterior side being a trifle the longer. It is moderately 



lis name was previously employed by Mr. .7. Y. Johnson for a remarkable Sea Anemone, Proc. Zool. Soc. Lond., 

 03. 



