3 



Centimeters 



Figure 1. — Gryphaea arcuala, Jurassic fossil. Specimen 

 No. 283 from the Museum of Comparative Zoology, 

 Harvard University. Dimensions: height S.5 cm., 

 depth 3.5 cm. 



Liuniirck's (1801) allocation of e.xtinct and recent 

 species of oysters to the genus Gnjphaea. Under 

 this generic name, which was published with a 

 diagnosis, Lamarck included nine nominal species, 

 some of which at the time of publication were 

 "nomina nuda" since they lacked diagnosis, but 

 other species were validated by citation of biblio- 

 graphical references (Hemming, 1951). Lamarck 

 had not designated the type species, and a selec- 

 tion of "types" was made by Anton (1839), who 

 designated fossil Gnjphara arcvafa (fig. 1) as type. 

 Dall (1898) and Anthony (1906) also selected G. 

 arcuata as type. A living species, Gryphaea aniju- 

 lata, was included by Lamarck (1801) but without 

 a diagnosis. 



Lanuirck (1819) further confused the nonuMi- 

 clature of the genus (ktrea when he again describcil 

 the genus Gryphaea. A longer list of species 

 included common oyster of Portugal and Medi- 

 terranean, Gryphaea angulafa, this time, however, 

 with a diagnosis (fig. 2). It was assumed l)y 

 Children, Grey, Fisher, Tryon, Stoliczka, and 

 Sacco (quoted from Dall, 1898: 671-GS8) that 

 G. aiKjulata is Lamarck's type species, an ojiinion 

 entirely without foundation. Anatomical and 

 embryological studies have demonstrated tliat 

 G. angulata has no characteristics of the fossils 

 Gryphaeidae. The species is simply another type 

 of oyster similar to the American species \('. 

 virginica), with a slightly twisted beak which only 



remotely resembles the curved beak of the 

 Gryphaea. 



Oysters are frequently found so closely adhering 

 to the substratum that their shells faithfully re- 

 produce the configurations and detailed structures 

 of the objects upon which they rest. For instance, 

 under the name of (ktrea tuherculata, Lanrarck 

 (1819) described a shell from the Timor Sea 

 (Netherland Indies) grown on a coral of the family 

 Astraeidae; this particular shell repeated the 

 tubercles and other structural elements of the 

 coral upon which it was resting. Other speci- 

 mens of the same species, but grown on a smooth 

 surface, were listed as different species. 0. 

 haliotidea of Australia, another Lamarckian species 

 assumed a shape of the abalone shell to which it 

 was attached. Oysters adhering to the shells of 

 Trochus maculatus repeated the granular structure 

 of this gastropod (Smith, 1878), while those grown 

 on branches of mangrove trees usually formed a 

 groove between the folds of the shell facing the 

 branch while the same species attached to the 

 trunk of the tree did not develop such structure 

 (Gray, 1833). 0. equestris found growing on 

 naWgation buoys (Galtsoff and Merrill, 1962) re- 

 peated the configurations of bolts and shells of 

 barnacles upon which they happened to attach 

 themselves. 



The influence of other factors of the envu-on- 

 ment on the shajje and sculjjture of oyster shell 

 has been reported by many investigators who 

 noticed that specimens growing in calm water on 

 flat surfaces have a tendency to acquu-e a round 

 shape and to have poorly developed umbones. On 

 soft bottom and overcrowded reefs the same species 

 tend to form long and slender, laterally compressed 

 bodies wath hookhke umbones. Lamy (1929) 

 oljserved tliat oysters attached to a pebble or shell 

 and, therefore, slightly raised above the bottom, 

 had deep lower valves, more or less radially ribbed. 

 This type of structure, according to Lamy, offered 

 greater resistance to dislodgment by currents or 

 wave action. 



Since Lamarck's inclusion of a hving estuarine 

 species, G. angulata, in one genus with the fossil 

 Jurassic and Cretaceous Gryphaeas was not ac- 

 ceptable to nuxny biologists, the question was 

 submitted for ruling by the International Commis- 

 sion on Zoological Nomenclature. The retention 

 of the name "Gryphaea" and the designation of G. 

 angulata as the type species of the genus Gryphaea 

 was favored by the "majority" of European zool- 



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