ISO MANUAL OF ZOOLOGY.' 



tute of the long tentacular appendages so characteristic of the 

 latter. 



In Cestum, 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." 



The Ctenophora may be divided into the following groups : 



A. EURYSTOMATA. Oral aperture large, occupying the whole of the 



oral extremity of the body. 



1. Beroida. The paragastric canals opening into a circum-oral 



ring. No tentacles. Ex. Beroe, Idyia. 



B. STENOSTOMATA. Mouth small and narrow. 



2. Saccate, No circum-oral canal; tentacles two. Ex. Pletiro- 



brachia, Eschscholtzia, HormipJiora. 



3. Lobatce. Body furnished with a pair of wing-like oral exten- 



sions or lobes. Ex. Bolina> Mnemia, Encharis, Lesueuria. 



4. Taniatie, Body ribbon-like ; no oral lobes ; two tentacles. 



Ex. Cestum. 



CHAPTER XVI. 

 DISTRIBUTION OF ACTINOZOA. 



i. DISTRIBUTION OF ACTINOZOA IN SPACE. 2. CORAL-REEFS. 

 3. DISTRIBUTION OF ACTINOZOA IN TIME. 



DISTRIBUTION OF ACTINOZOA IN SPACE. The Zoantharia 

 malacodermata appear to have an almost cosmopolitan range, 

 Sea-anemones being found on almost every coast ; some of the 

 tropical forms attaining a very large size. Whilst essentially 

 littoral and shallow-water forms, a few of the members of this 

 group have been found by the Challenger expedition to ex- 

 tend to great depths. Thus, as shown by Mr Moseley, 

 Edwardsia has been found at 800 fathoms, and CeriantJms 

 at no less than 2750 fathoms; while species of Actinia itself 

 go down to over 1000 fathoms. A few forms also (such as 

 ArachnactiS) Nautactis, Plotactis, Oceanactis, and Minyas) are 

 pelagic in habit, and live in the open ocean. The Antipathidcz 

 are principally inhabitants of warm seas ; but have been found 

 off the coast of Greenland ; while they extend to great depths. 

 The Alcyonidce are principally inhabitants of shallow water; 

 but the Pennatulida extend their range up to very great depths. 

 The Gorgonidcz are likewise mostly shallow- water forms, and 

 they attain their maximum in the seas of the tropics. The 



