150 Miscellaneous. 



This species is the giant of the family to which it belongs. Of the 

 three sjDecimens in the Collection, the largest measures rather more 

 than a full inch in length, and about three-fourths of au inch in 

 breadth, the other two being slightly smaller. They were sent to the 

 British Museum by Sir "W, Denison, Governor of Australia, who in 

 a letter to Dr. Gray informs him that they were taken "in water- 

 holes or lagoons on the plains, on the banks of the Wamoi (a river 

 which discharges itself into the Darling, and ultimately by the 

 Murray into the sea), in South Australia." They were collected by 

 Mr. W. Birch, who in a note to the Governor says : — " My attention 

 was first drawn to the Bivalves by observing them in motion, appa- 

 rently in search of food ; and until a specimen was obtained, I 

 was under an impression, from the rapidity of their movements, 

 that they vv^ere small fishes. Undeceived in this respect, I deter- 

 mined to ascertain, if possible, the means by which the mollusk 

 progressed. I observed that the serrated part of the shell was down- 

 ward and the valves were in constant motion, and that four antennae 

 were protruded from the shell, evidently for grasping food. The 

 anatomical structure of the animal appeared so much at variance 

 with other mollusks, that I preserved the specimens intact. I found 

 by experience that if the shells are immersed in tepid water for about 

 ten minutes, the animals will be sufficiently developed for minute ob- 

 servation." 



In compliance with Sir W. Denison's request that the name of 

 the collector " should be commemorated in connexion with the spe- 

 cies," I have named it Estheria Birchii. 



Magnitude, 1 inch in length, | of an inch in breadth. 



Hab. Pools of fresh water on the banks of Wamoi River, Au- 

 stralia. 



Mus. Brit. 



MISCELLANEOUS. 



O71 a Hijbrid betioeen Saturnia Pavonia-major and S. Pavonia-media 

 (Bombyx Pyri and B. Spini, Borc/ch.). By M. Guerin-Mene- 



VILLE. 



M.'Guerin-Menevtlle has brought before the Academy of Sciences 

 of Paris a case of hybridism between the two species of moths above 

 mentioned. He states that the hybrids were obtained by a German 

 dealer in insects, who sold them at forty francs apiece, and who 

 naturally would be unwiUing to sacrifice any portion of his profits to 

 an experiment upon the possible fecundity of the insects. The only 

 fact ascertained was that the males were far more numerous than the 

 females ; the four or five individuals sent to Paris were all males. 

 The male parent was S. Pavonia-tnajor. 



On comparing the hybrids with their parent species, they are 

 found to resemble the female more than the male in their general 

 coloration ; in size they are intermediate between the two species. 



