83 



"Mus. Lud. Uricae" he added a référence to Seba, pi. XCIII, figs. i, 2, both of which are 

 figures of a species of Malletis. In the twelfth édition of the "Systema" he replaced this last 

 citation by Seba, pi. XCI, figs. 6, 7, 8; the first tvvo figures agrée with the figure of Rumphius, 

 but figure 8 represents a form with a short auricle, and with its byssal gape more insinuated 

 below the anterior extremity of the hinge; this form was described later as canina by Lamarck. 

 In the same work he also cited Gualtieri, pi. XCVII, fig. 7, which is the figure of a form with 

 a very long, somewhat straight shell, and a very short auricle; this form was later named noj^ma 

 by RôDiNG and femoralis by Lamarck. 



Distribution : — /. isognomum is widely distributed in the Indo-Pacific. 



In the "Siboga" collection this species is represented by shells collected at Tuai (St. 258), 

 Saleyer Anchorage (St. 213) and Anchorage off Kilsuin, west coast of Kur Island (St. 250). 



2. Isognomon isognomum (Linn.) var. canina (Lamarck). 



1758. Concha Volsella dicta niinor etc., Seba, Thés., p. 181, pi. XCI, fig. 8. 



1773. UEqiierre Knorr, Délices des Yeux, VI, p. 23. pi. XIII, fig. i. 



1773. Der Winkelhaken Valentyn, Abhandl. Schneck. Muschel. p. [45, pi. XIII, fig. 3. 



18 17. Melina Isogomini Schumacher, Essai Nouv. Syst., p. iii, pi. II, figs. 4^,3. 



18 19. Perna canina Lamarck, Anim. sans Vertèb., VI, p. 141. 



1825. Ostrea Isognomon Wood, Ind. Test., p. 53, pi. XI, fig. 79. 



1830. Perna Isognomum Sowerby, Gen. Shells, II, fig. i. 



1841. Perna Isognomum Reeve, Conch. Syst., p. 147, pi. CVI, fig. i. 



1843. Perna Canina Hanley, Rec. Biv. Shells, p. 258. 



1845. Perna canina Catlow & Reeve, Conch. Nomencl., p. "j"]. 



1853. Perna isognomnm Deshayes, Trait. Elem. Conch., pi. XLV, figs. i, 2. 



1856. Ostrea isognomon Hanley in Wood, Ind. Test., p. 63, pi. XI, fig. 79. 



1858. Perna fimbriata, P. patibidum and P. vespertilio Reeve, Conch. Icon., XI, Perna pi. IV, 



figs. 18, 19, pi. VI, fig. 26. 

 1880. Perna isognomon var. canina von Martens, Môbius Beitràg. Meeresf, Mauritius, Seychell., 



P- 317- 



1891. Perna novoliollandiae, P. patibiilmn, P. vespertilio, P. fimbriata and ? P. aquila Clessin 

 in Martini Chemn. Conch. -Cab. (N. F.), VIII (i), Malleacea, p. 34, pi. X, fig. 2, p. 34, 

 pi. VIII, fig. 2, p. 37, pi. Xni, fig. 2, p. 38, pi. XIII, fig, 4, p. 43, pi. XYa, fig. I. 



1896. Perna vespertilio Casto de Elera, Cat. Sist. Filip., p. 798. 



1909. Melina isognomum var. canina Lamy. Mém. Soc. Zool. France, XXII, p. 339. 



1928. Pedalion vespertilio Faustino, Summary Philippine Mar. Freshvv. Mollusks, p. 25. 



1929. Isognomon isognomnm var. canina Dautzenberg, Faun. Col. Français., III, p. 566. 



The synonymy given above is based on a careful study of the literature and the collections 

 in the British Muséum (Nat. Hist.) London, and the "Siboga" collection. 



The var. canina of /. isognomzim has a comparatively broader, rather elongate, straight 

 or only slightly arched shell. The auricle is short and broad, somewhat triangular in outline, 

 and the byssal gape is more insinuated below the hinge-margin. 



Distribution : — /. isognomum var. canina has been recorded from such widely separated 

 areas as the Mascarenes in the Indian Océan, and the Philippines in the Pacific. Probably it is 

 found throughout the Indo-Pacific Reofion. 



In the "Siboga" collection there is a good séries of this interesting variety from Pulu 

 Sanguisiapo, Tawi Tawi Islands, Sulu Archipelago (St. 93), St. 164 (i°42'.5 S., i30°47'.5E., 



