76 THB VOYAGE OF H.M.S. CHALLENGER. 



The soft parts of two specimens and a few fragments of the shells adhering to 

 them were alone obtained. From these it is evident that the species is rather large, 

 probably about 20 mm. in length. The shell is excessively thin, prettily iridescent 

 within and faintly so on the outside, which is more or less covered with a thin filmy pah; 

 yellow epidermis, which towards the outer margin of the valves is produced into oldiquc 

 thread-like lines, and somewhat reflexed within. The sculpture consists of distinct 

 concentric lines of growth, a few subdistant hair-like radiating lines chiefly observable 

 near the outer mai'gin, and very minute rather irregularly scattered granules which 

 appear to be most numerous and more i-egularly arranged on the anterior side. The 

 umbones are white, smooth, incurved, and incline towards the front. The hinge-line is 

 rounded and quite toothless in both valves. The ligament is external, strongish, and 

 attached to the edge of the valves. 



I cannot discover any sufficient reasons for separating the Australian and American 

 specimens of this very interesting species. They agree exactly as regards the hinge, the 

 fragility of the valves, the epidermis, and the character of the sculpture, the Atlantic 

 example, however, exhibiting rather more distinct granulation. The animals also are 

 precisely alike, even the number of papillas surrounding the siphonal openings being 

 precisely the same, namely fifteen. This is another instance of the remarkable distribu- 

 tion of some deep-sea forms. 



Suljfamily Anatinin^. 



Anatina, Lamarck. 

 Anatina siphonafa, Reeve. 



Anatina siphonafa, Keeve, Conch. Icon., vol. xiv. pi. i. tig. 2. 

 Habitat. — Station 208, Philippine Islands, at a depth of 18 fathoms ; l>lue mud. 



The Challenger specimen is a little larger than the ty[:)e, and almost exactly of the 

 same form. I think it probable that Anatina Jiexuosa, Reeve, Anatina cumingii, 

 Valenciennes, Anatina amphora, Reeve, and one or two other so-called species, together 

 with that under consideration, are merely variations of one and the same form. 



Anatina elliptica (King and Broderip), juv. 



Anatina elliptica, King and Broderip, Zool. Journ., vol. v. p. 3.3.5. 

 Anatina dliptica. Reeve, Conch. Icon., vol. xiv. fig. 14. 

 Anatina elliptica, Griffith's Anim. Kingd., vol. xii. pi. xxii. fig. 3. 

 Anatina prismatica, Sowerby, Proc. Zool. Soc. Lond., 1834, p. 87. 



Testa juvenis fragilissima, oblonga, transversa, antice rotuudata, postice lata, arcuatim 

 truncata, inasquilateralis, alba, concentrice rugose striata, sulco obliquo baud profundo ab 



