134 MANUAL OF ZOOLOGY. 



simply curving round towards their apical extremities, .and 

 opening into the funnel directly. 



Amongst the Beroida the mouth extends entirely across the 

 oral extremity of the body; hence they have been termed 

 Eurystomata, the term Stmostomata being applied collectively 

 to all the other Ctenophora. 



The Beroidx further differ from Pleurobrachia in being 

 destitute of the long tentacular appendages so characteristic 

 of the latter. 



In Cesium, or " Venus's Girdle," " elongation takes place to 

 an extraordinary extent, at right angles to the direction of the 

 digestive track, a flat, ribbon-shaped body, three or four feet in 

 length, being the result." 



Divisions of the Ctenophora. — The following arrange- 

 ment of the Ctenophora has been adopted by Gegenbaur (see 



Greene) :— 



Order CTENOPHORA. 



Sub-order I. Stenostomata, 



Family I. Callymmid^. 



Body furnished with a pair of antero-posterior oral lobes, and other 

 smaller lateral appendages. Tentacles various, turned toward%the 

 mouth. 

 Family II. Cestid.«. 



Body ribbon-shaped, extended in a lateral direction, without oral 

 lobes. Tentacles two in number, antero-posterior, turned towards the 

 mouth. 

 Family III. Callianirid/es. 



Body produced into a pair of wing-like lateral lobes, bearing the cteno- 

 phores. Tentacles two in number, lateral, turned from the mouth. 

 Family IV. Pleurobrachiad^. 



Body oval or spheroidal, without oral lobes. Tentacles two in 

 number, lateral, turned from the mouth. 



Sub-order II. Eurystomata. 

 Family V. BeroiD/E. 



Body oval, elongated, without oral lobes. Tentacles absent. 



CHAPTER XVII. 



DISTRIBUTION OF ACTING ZO A. 



I. Distribution of Actinozoa in Space. 2. Coral Reefs. 

 3. Distribution of Actinozoa in Time. 4. Appendix. 



Distribution of Actinozoa in Space. — The Zoantharia mala- 

 codertnata appear to have an almost cosmopolitan range, sea- 



