144 48 
Pteria (Margaritifera) vulgaris, Schum. var. occa, Reeve. 
Avicula ocea, Reeve, Conchol. icon., X, 1857, Avicula, Sp. 24. 
(Meleagrina) occa, Reeve, Manrini u. Cuemnirz, Conchyl. Cabin., VII Bd. 3 Abth., p. 42, pl. 13, 
fig. 5. 
Koh Kram, 30 fathoms ('/2). 
Long. 28 mm., alt. 29 mm. 
Distribution: — Red Sea, Gulf of Aden (JoussEAumE). 
Professor Ep. v. MarTENS, to whom I sent the specimen for comparison, writes 
to me as follows: ‘‘vermuthlich occa Reeve, wenn man annehmen kann, dass bei 
der Ihrigen die Schuppen abgerieben seien.” A. H. Cooke’ and H.L. JAmMEson® are 
certainly right in considering A. occa, Reeve, a form of Marg. vulgaris, Schum. 
(= A. fucata, Gould).* The present species has probably a far wider distribution 
than that stated above, but to ascertain this, further investigations will be necessary. 
A. Grarnp! has collected what he believes to be its synonyms, and according to’ 
these its geographical distribution becomes considerably wider. 
Pteria (Margaritifera) nigra, Gould. 
Avicula nigra, Goutp, Proc. of the Boston Soc. of Nat. Hist., vol. 3, 1850, p. 309. 
= = — Un. St. Expl. Exped. Moll., p. 488, pl. 40, fig. 454. 
- tristis, DuNKER, Martini u. CHEMNITZ, Conchyl. Cabin., VII, 3 Abth., p. 44. pl. 14, fig. 3. 
East of Koh Chuen, 9—10 fathoms, shells. 
Long. 48 mm., alt. 38 mm. 
Distribution: — Singapore. 
A smaller specimen (long. 19 mm., alt. 16 mm.), which, with some doubt, I 
refer to the present species, was taken at Koh Kahdat in one fathom, on a sandy 
bottom. 
Pteria (Margaritifera) citrina, Dunk. 
Avicula (Meleagrina) citrina, DuNkenr, Zeitschr. f. Malakozoologie, IX, 1852, p. 78. 
= — Martini u. CHemnNitz, Conchyl., Cabin., VII Bd. 3 Abth., pp. 14 and 
71, pl. 3, fig. 4, and pl. 25, fig. 1. 
Pteria (Margaritifera) — -- JamESON, Proc. Zool. Soc. London, 1901, p. 383. 
Strand of Koh Kahdat (7/2). 
Long. 24 mm., alt. 25 mm. 
Distribution: — Dutch India (E. v. MARTENS in litt.). 
1 Annals and Magaz. Nat. Hist., Ser. 5, vol. 17, pp. 1836—37. 
2 Proc. Zool. Soc. London, 1901, p. 384. 
* A. PAGENSTECHER describes various forms of P. occa, Reeve, from the Red Sea in “Ueber die v. 
R. Kossmann am Rothen Meere gesamm. Mollusken,” 1877, p. 35. 
' Comptes rendus hebdomad. d. seances de la Soc. de Biologie, Paris, Tome 56, 1904, pp. 255—57. 
