1 AQUATIC BEETLES 63 



Lyonnet gave him some friendly help in the work. 

 Those who care to turn to the preface of Trembley's 

 famous treatise {Mcmoires pour servir a fJiistoire des 

 Polypes d'eau douce, 1744) will see how warmly 

 Lyonnet's services are acknowledged. He made all 

 the drawings, and engraved eight of them himself, 

 while Trembley is careful to note that he was not 

 only a skilful draughtsman, but an acute and experi- 

 enced observer. When the work was begun, Lyonnet 

 had never seen the operation of engraving a plate. 

 . Wandelaar, struck by the beauty of his drawings, 

 persuaded him to try what he could do with a burin. 

 I lis first essay was made upon the figure of a Dragon- 

 fly, next he engraved three Butterflies, and then, 

 without longer apprenticeship, he proceeded to 

 engrave the plates still required to complete the 

 memoir on Hydra. 



Lyonnet tells us that the larva of the Goat Moth 

 was not quite his earliest attempt in Insect Anatomy. 

 He began with the Sheep Tick, but suspecting that 

 the subject would not be popular he made a fresh 

 choice for his first memoir. Enough interest was 

 excited by the Traite Anatomique to call for the 

 fulfilment of a promise made in the preface that the 

 description of the pupa and imago should follow. 

 Hut though Lyonnet continued for some time to fill 

 his portfolio with drawings and notes, he never pub- 

 lished again. Failing eyesight was one ground of his 

 retirement from work. What he had been able to 

 finish, together with a considerable mass of miscel- 

 laneous notes, illustrated by fifty-four plates, was 

 published long after his death in the Memoires du 



