RESEARCH ON THE DIGESTIVE SYSTEM OF THE SCHIZOPODA 2 7 



In FiG. 14 the lovver portions of the plates S,, in the cardiac cliamber 

 arc attaclied to the external integument laterally. 



Tlie médian pièce 5, is moved chiefly by a pair of muscles which are 

 inserted at the anterior basai extremity ; leaving the point where they are 

 attached they diverge considerably and run in an oblique direction to the 

 external integument at each side of the œsophagus, fig. 3, 7. 9, 14. It is 

 to be noticed that the fibres pass between the cells which constitute the 

 matrix of the cuticle and are attached to the cuticle itself, fig. 7. 



The pyloric chamber is attached to the dorsal integument by a pair of 

 strong muscular bands, inserted at each side of its dorsal surface, at the 

 level in which section 15 has been eut. 



In the Schizopoda as in other Crustacea an internai skeleton is found, 

 consisting of muscular fibres which hâve undergone a peculiar modifi- 

 cation, and hâve become of a chitinous nature. A rigid system of bars is 

 thus formed which serves as a point of attachment for varions muscular 

 Systems. 



A transverse section is seen in fig. 6 through the principal bar of Alysis. 



Numerous muscle bands are attached to its extremities. 



In the same figure a pair of long muscular fibres are attached to the 

 bar and to the dorsal surface. 



We shall examine thèse muscles in détail in the histological chapter. 



This chitinous bar runs a considérable distance beneath the pyloric 

 chamber. 



Its longitudinal aspect is shown in fig. 3, br. sk. 



In the Mysis, another system of internai skeleton is found behind the 

 one that we hâve just described. 



It is of the same constitution, but possesses a pair of internai cavities 

 covered with a cuticle, fig. 20, br. sk. 



It serves for the attachment of a séries of muscle bands on the ventral 

 surface of the mouth, fig. 20, cl. p. 



Professor Ide has given a detailed description of the internai skeleton 

 as it is found in the Edriophthalmia. 



The mid-gitt. 



Without exact embryological détails we cannot define the limits of this 

 région. As far as we know, no certain data hâve been given by any author ; 

 Van Beneden does not attempt the question. 



