10 Charles GELDERD 



LET, After him, the homologies of the moveable pièces in the Decapoda and 

 the Edriophthalmia was admitted by the well known investigators. But, to 

 repeat, to endeavour to establish the homologies of ail the pièces which 

 make up the complicated structure of the stomach in the Crustacea, requires 

 a complète study of ail the pièces, with ail the détails of structure, in ail 

 the groups. This has not yet been done. 



In examining the stomach of Mysis, our attention was drawn to the 

 complexity of its stomach pièces. We therefore proposed to describe, as 

 fully as possible, the structure both anatomical and histological, of the 

 digestive system of the Schizopoda, to compare it with that of the Decapoda 

 and Edriophthalmia, as a contribution to the comparative anatomy of the 

 Crustacea, and for the study of the question of parallelism or non-paral- 

 lelism, in the évolution of the internai and external organs of the Ar- 

 thropoda. 



Brief descriptions are to be found hère and there in the différent 

 authors on the digestive system of the Schizopoda; the complexity of the 

 stomach apparatus.is generally admitted, but no complète anatomy has yet 

 been written. 



We hâve taken as type of the Schizopoda the Macrouiysis flexuosa. 

 After describing as fully as possible our type, we hâve pointed out the dif- 

 férences of structure that are found in the following species : 



Macvopsis slabberi. 

 Schistomysis omata. 

 Afysis viilgaris. 

 Schistomysis spiritiis. 

 Gastrosaccus spinifer. 

 Mysidopsis gibbosa. 

 Anchialus agilis. 

 Sir ici la. 

 Nyctiphancs coiichii. 



With regard to the stomach pièces, our research has led to the following 

 gênerai conclusion : the stomach of the Schizopoda possesses the saine struc- 

 tural plan as that of the Decapoda and the Edriophthalmia, and contains 

 several pièces homologous to the pièces of the stomach in those groups. 



Thèse pièces are five in number, and are found uniformly in thèse 

 groups, so différent from many points of view. 



