142 46 
Pteria (Electroma) zebra, Reeve. 
(Pl. II, Figs. 16—18). 
Avicula zebra, ReEve, Conchol. icon., X, Avicula, Sp. 36. 
— — —  Marrini u. CHemnirz, Conchyl. Cabin., VII, 3 Abth., p. 60, pl. 21, fig. 3. 
Koh Kram, 30 fathoms (2). Koh Mesan, 15 fathoms, stones (2). Between Koh 
Mesan and Koh Chuen, 25—38 fathoms, stones (6). 
Long. 3—12 mm. 
Distribution: — N. Male Atoll (Epa. Smirn). — Gulf of Manaar (STANDEN & 
Leicester), Tuticorin (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 Chuen; 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 Plumularia sp. As may be seen from the figures in PI. II, Figs. 16—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 Plumularia 
abielina, 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, Conchol. icon., X, 1857, Avicula, Sp. 22. 
Martini u. Cuemnirz, Conchyl. Cabin., VIL Bd. 3 Abth., p. 42, pl. 13, fig. 6. 
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, Schum. 
Perlamater vulgaris, SCHUMACHER, Essai d’un nouv. syst. d. habitat. d. vers test., 1817, p. 108, pl. 20, fig. 3. 
Margarilifera — - JAMESON, Proc. Zool. Soc. Lond., 1901, I, p. 384, Sp. 13. 
_ _~ _ W. A. HerpMan, Report on the Pearl Oyster Fisheries of the Gulf of 
Manaar, II, 1904, pp. 37—76, pl. 1—9. 
Avicula fucata, GouLp, Proc. of the Boston Soc. of Nat. Hist., II, 1850, p. 309. 
= = — Un. St. Expl. Exped. Moll., p. 441, pl. 39, fig. 551. 
— = — Reeve, Conchol. icon., X, Avicula, Sp. 74 (pl. XVII). 
1 Madras Government Museum, Bulletin No. 3, Ramésvaram Island and Fauna of the Gulf of 
Manaar, 2 ed., Madras 1895, p. 130. 
* Zoology, vol. 7, 1883, p. 21, pl.3. The specimen was from Prince Edward’s Island, 150 fathoms (?). 
