142 46 



Pteria (Electroma) zebra, Reeve. 



(I'l. II. Figs. ll)-18). 



Ai'icula zebra, Rkeve, Concliol. icon., X, Avicula, Sp. 36. 



— — — iM,vnTiNi u. CHKMNn/,, Concliyl. Cabin.. VII, ;i Aljtii., p. liO, pi. '21, lig. 3. 



Koh Kram, 30 fathoms (2). Koh Mesan, 15 fathoms, stones (2). Between Koh 

 Mesan and Koh Cliuen, 25—38 fathoms, stones (6). 



Long. 3 — 12 mm. 



Distribution: — N. Male Atoll (Edg. Smith). — Gulf of Manaar (Standen & 

 Lkicester), Tulicorin (Thurston), Port Elizabeth (Sowerby), Port Denison, Queens- 

 land ("Alert"), Moreton Bay, Australia (Cuming), King Island, Tasmania (Tate & May). 



A variety, with twelve pale-brown lines radiating from the umbo, (without 

 the characteristic oblique lines) was taken, to the number of three specimens in 

 30 fathoms at Koh Cliuen; it was not found attached to any object as was the 

 type form. — The specimens, from the localities mentioned above, were all found 

 attached to Plumiilaria sp. As may be seen from the figures in PI. II, Figs. IG — 18, 

 the mimicry is exceedingly striking; the beautiful colour-ornamentation upon the 

 valves resembles exactly the branches of the Hydroid. Reeve describes and figures 

 it as attached to a Sertularia. Thurston' also mentions its mimicry in relation to 

 Aglaophenia urens upon which it settles. G. J. Allman mentions in the Report 

 on the Hydroids of the Challenger Expedition,- when treating of Plumiilaria 

 abieiina, that "The specimen had numerous individuals of an Avicula-like fry 

 adhering to it." Judging from the figure it can, however, scarcely be A. zebra, Reeve. 



Pteria pulchella. Reeve. 



Avicula pulchella, Reeve, Conehol. icon., X, 1857, Avicula, Sp. 22. 



— — — Martini u. Chemnitz, Cunchyl. Cabin., VII Bd. 3 Abth., p. 42, pi. 13, fig. (i. 



East of Cape Liant, 9 fathoms, shells (1). 

 Long. 20 mm., alt. 16 mm. 



Distribution: — Philippines, East and South Australia. 



On account of the small size of the specimen, there may perhaps be a slight 

 doubt concerning the correctness of the determination. 



Pteria (Margaritifera) vulgaris, Sebum. 



I'erlatnalcr inilgaris, Schumacher, Essai d'un nouv. syst. d. habitat, d. vers test., 1817, p. 1U8. pi. 2U, lig. 3. 

 Margaritifera — — Jameson, Proc.Zool.Soc-. Lond., 1901, I, p. 384, Sp. 13. 



— — — W. A. Herdman, Report on the Pearl Oj'ster Fisheries of the Gulf of 



Manaar, II, 1904, pp. 37— 76, pi. 1-9. 

 Avicula fitcala, Gould, Proc. of the Boston Soc. of Nat. Hist., Ill, 18ÖU, p. 309. 



— — - Un. St. Expl. Exped. Moll., p. 441, pi. 39, fig. 551. 



— — — Reeve, Conchol. icon., X, .4(>ioi!/a, Sp. 74 (pi. XVII). 



' Madras Government Museum, Bulletin No. 3, Ràmésvaiam island and Fauna of the Gulf of 

 Manaar, 2 ed., Madras 1895, p. 130. 



- Zoology, vol.7, 1883, p. 21, pi. 3. The specimen was from Prince Edward's Island, 150 fathoms ('?). 



