80 



hinge line of these Adula bears 12—13 large lateral teeth (see Figure 43). The 

 larva is opaque, brownish. The large dark red eyes are very distinct. The shell 

 of the veliconcha is 320—350 |im long. The larva of A. falcatoides is very 

 similar in structure to the larva of ^. simpsoni described by Rees (1950) from 

 the North Sea. 



Ecology 



Larvae of A. falcatoides are observed in the second half of summer in 

 Vostok Bay, mainly in August, at a water temperature of 18— 20°C. 



No data on the morphology and ecology of this species were found in the 

 literature. 



BOUC ARD'S ARC A, ARC A BOUCARDI JOUSSEAUME 



(Arcidae) 



Veliconcha 



The shell is equivalve and round, with its anterior margin narrower than 

 the posterior (see Figure 54, C). The umbones form at a shell length of more 

 than 150 jim; they are broad, not exceeding the hinge line in length, but equal 

 to it. In a developed veliconcha, there are six large lateral teeth along each 

 margin of the hinge line and ten central teeth, which are half the height of the 

 lateral; thus there are eight teeth on each side. The provinculum is devoid of 

 teeth. Large bright eye spots appear in larvae 210 jim long. Larvae settle with 

 an average shell length of 224 ^tm. 



Ecology 



Area larvae are found in the plankton of Vostok Bay (Peter the Great Bay) 

 in July-August. 



The morphology of Boucard's area has been reported by Kulikova and 

 colleagues (1987). 



GIANT OYSTER, CRASSOSTREA ^7045 THUNBERG 



(Ostreidae) 



Veliconcha 



The shell is inequivalve. The left valve differs from the right in- shape and 

 size, being larger, more convex, and having a very well-developed umbo that 

 is much higher than on the right valve. The right valve is smaller than the left, 

 flattened, and with a low, round umbo. The height of the shell is somewhat 

 greater than its length. The anterior margin is longer than the posterior. The 



