RESEARCH ON THE DIGESTIVE SYSTEM OF THE SCHIZOPODA 37 



DORSAL DIVERTICULA 



1. Schistomysis ornata. Unpaired; heliciform ; summit directed towards intestine, fig. 32. 



2. Mysis vulgaris. Unpaired ; like Macromysis flexuosa. 



3. Schistomysis spiritus. Unpaired; summit pointed; slightly directed towards intestine. 



4. Gastrosacctis spinifer. Paired ; tubes lie close together ; summit directed towards stomach, 



FIG. 31. 



5. Mysidopsis gibbosa. Unpaired ; feeble devellopment ; summit directed towards stomach. 



DIGESTIVE GLANDS. 



1. Schistomysis omata. Same as in Macromysis flexuosa. 



2. Mysis vulgaris. More than one glandular ridge in each of the long pairs of tubes. 



3. Schistomysis spiritns. Same as m Macromysis flexuosa; ordinary secreting cells are very 



large in ail the tubes. 



4. Gastrosacciis spinifer. Glandular ridges of feeble development in each of the five 



pairs of tubes ; more than one in each tube ; ordinary se- 

 creting cells very large. 



5. Mysidopsis gibbosa. More than one glandular ridge in each of the long pairs of tubes. 



AU the above mentioned species hâve two pairs of latéral grooves in 

 the médian pièce ^3 except Gastrosacciis spinifer which, with Anchialiis and 

 Siriella, possesses three pairs. 



We hâve not found any structural différence between the anatomy of 

 Mysis kervillei and that oi Schistomysis ornata; the dorsal diverticulum so 

 distinctive in the other species is in both of thera of exactly the same shape 

 and structure. 



Anchialus agilis. 



The œsophagus in this species is comparatively longer than that of 

 our type; the stomach, on the other hand, is considerably reduced, fig. 3, 

 33. The cardiac chamber is of an oval shape, its anterior wall slightly in- 

 vaginated in the cephalic part lies against the cephalic ganglia. A short 

 epithelial fold runs for some distance transversly along the dorsal surface 

 of the cavity. 



This fold is seen in vertical section in fig. 33,^. 



The latéral plates S^ are of the same nature and disposition as those 

 of our type, fig. 34. 



The ridge c is large and cone-shaped. 



In comparing the vertical section of Anchialus with that of our type, 



