100 Miscellaneous. 



ova during the various phases of incubation and hatching ; for the 

 female does not remain fixed during oviposition like the Coccida; 

 and the Aphis above mentioned, but lays successively in several 

 nests. 



Up to the present time nothing of this kind had been observed 

 among the Acarina parasitic upon animals ; but chance has just 

 made me the witness of an exactly similar fact upon a bird. I 

 was preparing to dissect an American Grosbeak ( Cardinalis fulgens, 

 Bonap.), when, having stripped off the feathers of the thorax, I 

 was struck by the presence of numerous white spots with which 

 the naked median and sternal part of the skin which covers the 

 lower part of the breast was sprinkled. I have preserved this 

 portion of the skin stretched upon a plate of glass. 



Under the lens these little white patches have the aspect of 

 small spots of mould ; but under the microscope, especially after 

 soaking in glycerine, which renders them diaphanous, these spots 

 are found to be composed of a fine tissue, beneath which appears a 

 group of eggs in different stages of incubation, empty egg-shells, 

 and small yellow Acarines in process of escaping from these enve- 

 lopes, or which have already escaped from them. These Acarines 

 are nothing but octopod larva?, which, from the anatomical charac- 

 ters of the rostrum and legs, it is easy to recognize as belonging to 

 the species which I have named Cheyletus heteropalpus in a memoir 

 devoted to the description of a new group of Acarina parasitic on 

 Rodents and Birds, with which I have established a tribe of Cheyle- 

 tides parasites *. 



In his fine investigation of the anatomy and physiology of the 

 plumicolous Sarcoptides f, Professor C. Robin has shown that these 

 deposit their eggs in small masses at the axils of the barbs of the 

 feathers. I thought that my parasitic Cheyletides acted in the same 

 manner, seeing that they livo with them and even hunt after them ; 

 but I had never met with their eggs, which are remarkable and 

 very large (0-18 x 0*11 millim.), with those of the plumicolous 

 Sarcoptides. The observation which I have just described shows 

 how these eggs are laid and what precautions the Cheyletides 

 take to protect them — a fact which singularly approximates them to 

 the Tetranychi, with which, moreover, they are allied by their 

 organization. It shows, in addition, that the larvas of this species 

 are octopod when first hatched — a character which is not possessed 

 by those of the Tetranychi, nor even by those of the wandering 

 Cheyletides, such as Cheyletus eruditus. — Comptes Rendus, June 7, 

 1880, p. 1371. 



* Journ. de l'Anat. et Physiol. 1878. 

 t Comptes Rendus, April 30, 18G8. 



