CTENOPHORES OF THE ATLANTIC COAST OF NORTH AMERICA 



is in the plane of the pole-plate, while its narrow axis is in the plane of 

 the tentacles when these are present. This buccal chamber is commonly 

 called the "stomach," but its walls are of ectoderm and bear cilia, which 

 are especially well developed in the Beroidas, where they occur in linear, 

 longitudinal areas extending from the lips inward. This chamber is 

 certainly a food receptacle, and we will call it the stomodaeum. 



The stomodseum leads into the entodermal part of the gastric cav- 

 ity, a laterally compressed chamber called the ftmnel or infimdibulum. 

 The wide axis of the fimnel is perpendicular to that of the stomodaeum 

 and it lies in the plane of the two tentacles to the basal-bulb of each 

 of which it sends a canal. It also sends a canal upward to the sense-organ, 

 and this axial vessel, which is called the funnel-tube, opens by a pair of 

 excretory pores on two diagonally opposite sides of the pole-plate. In the 

 Beroidae there are two lateral funnel-tubes, one to each excretory pore. 



Tnsv 



-msv 



Fig. I. — Diagram illustrating characters of central part of gastro- vascular 



system of ctenophores. 

 Fig. 2. — Diagram showing character of canal-circuits in Lobatce. Tentacles, 



tentacular canals, ciliary combs, and auricles are omitted. 



In addition to the two tentacular vessels and the axial funnel-tube, 

 the funnel gives rise to four interradial vessels, which arise typically at 

 an angle of 45° with the stomodaeal and funnel axes. In the Cydippidae, 

 however, the four interradial vessels do not arise directly from the funnel, 

 but the funnel-chamber gives rise to a pair of side tubes called the per- 

 radial vessels, pr, figs. 4 and 5, pages 11 and 12, from the sides of which 

 the four interradial canals arise. In any event the four interradial canals 

 soon bifurcate and each of their eight adradial branches leads to a row of 



