34 Charles GELDERD 



2. Other species. 



The other species of Schizopoda that we hâve studied possess the same 

 gênerai structure in their digestive system as the Alacroinysis flexitosa. 

 They possess ail the typical pièces of the stomach; their digestive glands 

 and intestine are constructed upon the same type, exception, however, 

 must be made for Nyctiphaues. 



The greatest structural différences, amongst the Mysidse, are to be 

 found in Macropsis. In the case of the other Mysidse it will only be neces- 

 sary to point out slight variations. 



More important différences of détail are found in Anchialiis, Siriella 

 and Nyctiphaues. 



Macropsis Slabberi. 



A vertical section through the médian plane of this animal is shown 

 in FiG. 26. 



It will be noticed at once that the passage into the stomach from the 

 exterior is very m uch longer than in our type, cf. fig. i. 



The buccal cavity is of great size; the œsophagus runs vertically into 

 the ventral surface of the cardiac cavity. 



On the other hand the cardiac cavity is very much reduced. 



There is no anterior invagination into the cephalic région. 



It is in the form of a tube, with a lumen a little more than twice the 

 width of the œsophagus, fig. 26, 27. 



It possesses, however, the typical latéral pièces S^, with the ridge c. 



The pièces S, are of a much simpler constitution than the correspon- 

 ding ones of the other Mysidaî, fig. 27. 



Their direction in the cardiac chamber is shown in the pointed Unes, 

 fig. 26, S^. 



The pièces Sj stand out as prominent reliefs in the cavity with their 

 internai surfaces armed with strong spines curved upwards, fig. 27. 



The Macropsis possesses neither teeth nor hooks. 



The feeble development of the masticating apparatus of the cardiac 

 chamber, seems to be compensated by the large buccal orifice with its cor- 

 respondingly powerful paired appendages and long œsophagus. An impor- 

 tant structural différence is to bc observed in the absence of the arms br, 

 br^ Connecting the paired plates 5, with the pyloric folds S,s SJ; there is 



