196 Miscellaneous^ 



allied to that which one of us * had already described as occurring 

 iu Palitmon serrafus and P. rectirostris. 



We have since had occasion to observe in the muscles of the 

 Craj'fish a parasite which likewise belongs to the group of the 

 Sporozoa, but which exhibits somewhat remarkable differences from 

 the foregoing forms. 



Thanks to the kindness of M. Contejean we have been able to 

 examine fragments of Crayfish muscles from the Department of the 

 ]>oubs, which in the fresh state exhibited that remarkable opacity 

 to which we have already drawn attention in Grangon and Pakemon. 



In sections of these muscles we have found that the fibres are 

 attacked by a parasite in different stages of development. 



At certain points the muscle-fibre is found to be crammed with 

 little ovoid spores having a clear vacuole at their large extremity. 

 The appearance of these spores reminds us of those of the Micro- 

 sporidia, of Glugea, and of the parasites of Crangon and Palcemon. 

 They are much smaller than the spores in Crangon and iu size 

 approach those in Palcemon. 



By the side of these spores younger stages of the parasite are 

 found, represented by nucleated masses of protoplasm. Our obser- 

 vations, though they are as yet very incomplete, have nevertheless 

 enabled us to determine that this organism differs from the parasite 

 of the Crangon and of the two species of Palcemon in the mode of 

 the development of the spores. These, instead of being formed in 

 a group of eight in each sporogenous vesicle, are produced in variable 

 but always larger numbers. In this character the parasite of the 

 Crayfish approaches the Mierosporidia and certain forms of the 

 Myxosporidia. 



As regards the group to which this parasite ought to be assigned, 

 since wc have not had fresh material at our disposal we have not 

 been able to study the structure of the spores sufficiently thoroughly 

 in order to pronounce an opinion upon the point. 



The presence of this sporozoon in the muscles of the Crayfish 

 offers a double feature of interest : it causes our first observations 

 to extend to a larger number of species of Crustacea, and, moreover, 

 it seems that it ought to be of a certain practical importance from 

 the point of view of the etiology of the disease which for several 

 years past has destroyed the Crayfish of our watercourses in the 

 cast. — Gomptes renclus des Seances cle la Societe de Biologie (Seance 

 du 30 juillet, 1892) : from a separate impression communicated by 

 the Authors. 



des crustaces d6capodes," Comptes rendus de la Societe de Biologie^ 

 June 2^), 1892 (Anu. & Mag. Nat. Hist. ser. 6, vol. x. pp. 342-344). 



* Henaeguy, " Note sur un parasite des muscles du Palcemon recti- 

 rostris,'''' jNleiuoires publics par la Societe philomathique a I'occasion du 

 ceutenaire de sa foudation (1888). 



