PERRAXJLT AND HIS COLLEAGUES 235 



arteries nor veins in connection with it. The following 

 statement is remarkable : " J'ay vu par hazard que la 

 grande espece de Moule d'^tang, dont j'ay parl^, volti- 

 geoit sur la superficie de I'eau." 



M^ry (1710) notes the enclosure of the rectum of 

 Anodon in the heart, and describes the pericardium. 

 He too believes that Anodon can rise to the surface of 

 the water. He calls the external gills the ovaries, not 

 an unnatural mistake, seeing that in the breeding season 

 they are loaded with eggs. 



Insects and Crayfish 



Poupart (1704) describes the structure, life-history 

 and mode of life of the ant-lion. He is struck with the 

 resemblance of the imago to the dragon-fly, and calls 

 both of them " demoiselles." His figures are excellent. 

 In another memoir he gives an account of the frothing 

 hopper (the insect found in cuckoo-spit). 



Geofiroy the younger gives in 1709 an account of 

 " crabs' eyes," calcareous concretions found in the cray- 

 fish, and at this time regularly prescribed by physicians. 

 Gesner, Agricola and Belon had said that the concretions 

 form in the brain ; Geofiroy verifies the statement of 

 Van Helmont that they form in the stomach. He shows 

 that they are corroded and ultimately dissolved at the 

 time of moult, when the lining of the stomach and 

 intestine is shed ; he goes too far, however, in saying 

 that both stomach and intestine are destroyed at this 

 time. 



The astronomer Maraldi (1712) determined the angles 

 of the rhombic plates which form the bases of the cells 

 of the hive-bee. Kcenig (1739) showed the minute 

 correspondence of these angles with the form most 

 economical of wax. There is reason, however, to 



