196 Mi'scellaneouf^ 



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

 in Fdlirmon serratiis and P. recti rostris. 



We have since hud occasion to obsorvo in the muscles of the 

 Crayfisli a parasite which likewise belongs to the group of the 

 iSporozoa, Init which exhibits somewhat remarkablo differences from 

 the foregoing forms. 



Thanks to the kindness of M. Contejoan we have teen al)lo to 

 examine fragments of Crayfish muscles from the Department of the 

 Doubs, which in the fresh state exhibited that remarkable opacity 

 to which we have ;Jrcady drawn attention in Crani/on and Pahemon. 



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

 attacked by a parasite in different stages of development. 



At cei'taiu points the muscle-fibre is foimd 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 Ghir/ea, and of the parasites of Cramjon and Pulcemon. 

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

 approach those in Pulcemon. 



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 Cranrjon and of the two species of Puhemon in the mode of 

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

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

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

 Crayfish approaches the Microsporidia and certain forms of the 

 Myxosporidia. 



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

 since we 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 o])inion upon the point. 



The presence of this sporozoon in the muscles of the Crayfish 

 offers a double feature of interest : it causes our first obsei-vations 

 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 

 east. — Conipfes rendus d(S Seances de la Societe de Diolofjie (JSeance 

 du 80 juillet, 181.'2) : from a separate impression communicated by 

 the Authors. 



des criistace* d^capodes," Comptes rendus de la SociettS de Biologies 

 June 2"), 18U2 (Ann. & Mng. Nat. Hist. ser. G, vol. x. pp. 312-;i44). 



* Henaoguy, "Note sur un para.sito des muscles du Vala-mon recti- 

 rostrtK,'" .Meuioires publios par la SociOte philoniatliiiiue a I'ucca-iion du 

 Cjnteiiaire de sa foudatiou (1?588). 



