86 INVERTEBRATE MORPHOLOGY. 



and known as the gonotheca (Fig. 39, go). On account of the 

 presence of these cups the polyps of this order are sometimes 

 termed calyptoblastic. In the typical Campanularian polyp 

 colonies, such as those of Eucope or Ubelia, no further differ- 

 entiation of the polyps is found, but in the family Plumulari- 

 dae in the neighborhood of each of the small hydrothecse there 

 are one or more slender extensible polyps lacking mouth and 

 tentacles whose eudoderm is a solid axial cord, while the 

 ectodernial cells send off long, streaming, pseudopodia-like 

 processes, these polyps apparently playing the part of food- 

 providers for the colony. 



The medusae (Fig. 43) are usually very shallow bells, with 

 numerous hollow tentacles depending from the margin, and 



resemble the Trachyniedusse in 

 that the reproductive organs 

 develop on the line of the ra- 

 diating canals. Of these there 

 are in the majority of cases 

 four, though occasionally, as in 

 jffiquorea, they may be very 

 numerous. Sense-organs are 

 always present at the margin of 

 the bell and, as in the Trachy- 

 FIG. 43.fflegmatodes tennis, Ag. medussB and Narcomedusa?, are 



always otocysts, the rnedusse 



belonging to the vesiculate category. A marked difference 

 obtains between the otocysts of the Leptomedusfe and those 

 of the two preceding orders in that the calcareous crystals 

 are in the former developed in ectoderm cells. The otocysts 

 furthermore primitively occur on the inner surface of the 

 velum, where they are lodged in a slight depression, which 

 may, however, deepen so much that the otoc} T sts appear to be 

 imbedded in the substance of the bell. 



In the typical Campanularians free-swimming medusre are 

 developed, and according as the polyps or the medusae attract 

 especial attention the order may be termed that of the Cam- 

 pauularise or that of the Leptomedusa3. In a few forms, such 

 as Rhegmatodes, up to the present no polyp generation is 

 known to occur, and conversely in certain genera, such as Ser- 



