321 



As was pointed out by Deshayes ^) Lamarck in 1818 confused under the name A. iruncata 

 two species, but the Pacific species was neither described nor given a name till Sowerby published 

 a good figure of it under the name A. rostrata in 1842; Reeve however in "Conchologia 

 Iconica" apparently in ignorance of Sowerby's work still described the species as A. truncata 

 Lamarck. I hâve also no doubt that A. marilina ^) (pi. II, fig. 10), A. Boschasina (pi. II, fig. 13^, 

 A. liniicola (pi. III, fig. 27) and probably A. Tasmanica (pi. III, fig. 20) described by Reeve 

 in his work cited above are also synonyms of Sowerby's L. rostrata. Further, as Reeve stated, 

 it is the species for which Valenciennes had proposed the manuscript name A. olorina "). A 

 good description of the species was published by Hidalgo. 



Distribution : — L. rostrata has been recorded from the Philippines, while the species 

 which I hâve suggested as its synonyms are from Australia, Tasmania and Japan. 



The "Siboga" Expédition collected a single shell of this species from the Anchorage off 

 Beo, Karakelang Islands (St. 130). The measurements of this spécimen are: — Length 39.5 mm., 

 height 19 mm., diameter 15 mm. 



Family Myochamidae. 

 Genus Myadora Gray. 



1840. Myadora Gray, Ann. Mag. Nat. Hist., (3), IV, p. 306. 



1840. Myadora Gray, Synop. Brit. Mus., p. 136. 



1844. Myadora Reeve, Conch. Icon., II, Myadora, pi. I (explanation). 



1847. Myodora Gray, Proc. Zool. Soc. London, p. 191. 



1856. Myodora Adams, H. & A., Gen. Rec. MolL, II, p. 371. 



1880. Myodora Smith, Proc. Zool. Soc. London, p. 579. 



1887. Myodora Fischer, P., Man. ConchylioL, p. 11 59. 



In spite of Gray later altering the name Myadora to Myodora and Smith adopting the 

 latter spelling, the correct name of the genus would be Myadora^ as was originally published 

 by the author. 



For a detailed account of the genus référence may be made to Smith's paper cited 

 above. The génotype is Myadora brevis (Sowerby). 



I. Myadora weberi sp. nov. (Plate VII, figs. 11, 12). 



The following is a description of this new species : — Species of moderate size ; shell 

 compressed, fairly thick, subtrigonal, obliquely truncated posteriorly, acutely rounded anteriorly ; 

 posterior dorsal slope very incurved, slightly shorter than almost straight anterior slope, ventral 

 margin very regularly arcuate ; lower deep valve very shallow, with a deep linear dépression 

 near the posterior dorsal margin, corresponding to a curved ridge on outer surface of valve-, 

 upper flat valve with a shallow dépression about middle ; sculpture of lower deep valve more 

 impressed, consisting of concentric striae, with a few deeper grooves corresponding to régions 

 of growth. Shell of a light yellowish colour, nacre pearly white. 



i) Deshayes, G. P., in Lamarck, Anim. sans Vertèb., VI, pp. 77, 78 (1835). 



2) As Anatina maritima in the Index. 



3) According to Hidalgo the spécifie name was A. olar (op. cit., p. 297). 



SIBOGA-EXPEDITTE ISOlC. 4I 



