1901.] MOTHER-Or-PEARL OYSTERS. 389 



Species 23. Margaritifera radiata. 



Avicula radiata, Leach, 1814, vol. i, pi. 43, p. 98 ; ? West 

 Indies. 



Avicula squamulosa, Lamarck, 1836, tab. 7, p. 100; Brazil. 

 Avicula squamulosa, Lamarck, d'Orbigny, 1847, torn. 5, p. 658, 

 no. 761 ; Eio de Janeiro, coasts of Brazil, Antilles (Cuba, 

 Martinique, Guadeloupe, and Santa Lucia). 



Avicula jiahellum, Eeeve, 1857, sp. 7 ; hab. Venezuela. Type 

 in B.M. 



Avicula (Meleagrina) Jiahellum, Eeeve, Danker, 1872, p. 20, 

 tab. 6. fig. 1 ; hab. Porto Cabello, Venezuela. 



Avicula alaj^erdicis, Eeeve, 1857, sp. 10 ; xintilles. (Type 

 apparently not extant in British Museu.m.j 



Avicula assula, Eeeve, 1857, sp. 40; Antilles. (Type apparently 

 not extant in British Museum.) 



[Probably also the following species of Dunker : — 



Avicida {Meleagrina) echinus, Dkr. 1872, p. 40, fab. 13. fig. 2; 



Havana. 



„ „ Jiorrida, Dkr. 1872, p. 11, tab. 2. fig. 4, 



tab. 15. fig. 2; Venezuela and Antilles. 



„ „ longisquamosa, Dkr. 1872, p. 12, tab. 2, 



fig. 6 ; Porto Cabello, Venezuela. 

 ., „ olivacea, Dkr. 1872, p. 17, tab. 4. fig. 5 ; 



Antilles. 

 „ „ tamsiana, Dkr. 1852, p. 78; 1872, p. 15, 



tab. 4. figs. 1 & 2; Porto Cabello, 

 Venezuela.] 

 The West Indian Pearl-Oyster. 



This species has been treated to a number of synonyms, mostly 

 based upon characters of a nature quite valueless for systematic 

 purposes. Lamarck and d'Orbigny both emphasize the great 

 variability of colour in this shell. It remains yet to be proved 

 that there is more than one species of Margaritifera in the West 

 Indies and on the Atlantic Coasts of Tropical America. 



The West Indian Pearl-Oyster yields pearls in many localities, 

 but is practically valueless as Mother-of-Pearl. Conchologically, it 

 seems to be closely allied to the Lingah shells, but the posterior 

 process of the hinge is smaller, and the form often more nearly 

 approaches to that of the subgenus Electroma. 



Species 24. Margaritifera lurida. 



Avicula lurida, Gould, 1850, p. 310; 1852, p. 440. pi. 39 

 fig. 550 : Fiji Islands. 



Specimens in the British Museum, coll. J. Brenchley, Esq., from 

 Tongatabu, Friendly Islands, are quite in agreement with Gould's 

 figure and description of Avicula lurida. At first sight this species 

 suggests a small convex example of M. margaritifera, but the 

 presence of hinge-teeth and of a sinus in the posterior margin 

 proves this resemblance to be purely superficial , 



Proc. Zool. Soc— 1901, Vol. I. No. XXVI. 26 



