24 Charles GELDERD 



At the posterior portion of the pièce, fig. 10, post., the entrance to the 

 grooves is seen as a hollowed omt oval cavity, cf. fig. 17, which is a trans- 

 verse section through the entrance to the grooves. 



Thèse entrances are close to the entrances of the digestive glands. 



In front they terminate blindly, fig. lO, ant., fig. 14. 



Our préparations show us that thèse grooves are gencrally filled with 

 the sécrétions from the digestive glands. 



The same dispositions are found in ail the Schizopoda, except Nycti- 

 phanes. 



It is to be noticed that the spines terminate freely ; the grooves are not 

 intracuticular cavities. 



Exactly the same disposition is found in Gammarus. 



Professor Ide in describing them as intracuticular cavities, failed to 

 observe the comb-like formation of the spines. 



We may mention hère, that in the shrimp there are ten pairs of thèse 

 grooves in the inferior médian pièce. 



The posterior face of the pièce 5, rises in a curved Une, fig, 3, covered 

 with small spines directed vertically, fig. 16, 18. 



Opposite to the latéral faces of the médian pièce are the paired plates, 

 5„ FIG. 9, 13 to 17. 



They are formed by élévations of the epithelium in this région, a short 

 distance behind the anterior end of the cavity. 



In horizontal sections they hâve a convex surface, fig. 14. 



In front and at each side of the anterior end of the cavity, the plates 

 5, form with the base of the médian pièce S^, two culs de sac, fig. 14. 



The convex surfaces of the plates S^ are inserted in the concave latéral 

 faces of the médian pièce 5i, fig. 14. 



In transverse sections the latéral plates S^ are somewhat concave, 

 FIG. 15, 17. 



They rise above the level of the suinmit of the médian pièce where 

 they terminate in the folds SJ. 



Between the latéral plates and the pièce 5, two deep channels, or 

 grooves, are thus formed, fig. 15, 17. 



The direction which they take is seen in fig. 14; in front they terminate 

 in the culs de sac that we hâve already pointed out ; behind they form 

 narrow passages at each side of the wide posterior surface of the pièce 5^, 

 in front of the opening of the digestive glands. 



When mounted entire, the latéral pièces présent a singular appearance. 



