103 



Ecology 



Larvae of Zirfaea are found in the plankton of Busse Lagoon (southern 

 Sakhalin) and Peter the Great Bay in small numbers and are seen in August- 

 October at a temperature of 10-20°C. In Sond Strait (Ersund) in Danish 

 waters, larvae of Z. crispata are found in the plankton throughout the year, 

 except in March, April, and May. The maximum number is observed at the end 

 of summer-early autumn. 



The morphology of the larvae of Z crispata has been reported in many 

 works (Werner, 1939; J0rgensen, 1945; Sullivan, 1948; Rees, 1950). 



JAPANESE BARNEA, BARNEA JAPONICA (YOKOYAMA) 



(Pholadidae) 



Veliconcha 



Larvae large and roundish. The shell margin is broadly oval. The shoul- 

 ders are short and roundish, with the anterior shoulder slightly longer than the 

 posterior. The umbones are narrow and high (see Figure 41 C). The hinge line 

 is short. Concentric striation is visible on the hollow valves. A marginal band 

 is present. The central tooth on the right valve is two to three times longer than 

 the short front tooth. Before metamorphosis, another smaller tooth becomes 

 distinct on the right valve behind the large tooth. 



Ecology 



Larvae of Barnea are found in the plankton of Vostok Bay (Peter the Great 

 Bay) in the warmest months of the year, i.e., July— August, at a temperature 

 of 15-20 °C. 



The larva of this species is not described in the literature. 



