72 



MANUAL OF ZOOLOGY. 



present. l The reproductive organs are in the form of gono- 

 phores, ivhich vary much in structure, and arise from the sides 

 of the polypites, from the coenosarc, or from gonoblastidia.' 

 (Greene.) 



The hydrosoma of the Corynida may consist of a single 

 polypite, as in Coryomorpha and Vorticlava, or it may be com- 

 posed of several united by a coenosarc, as in Cordylophora 

 (Jig. 13 a). The order is entirely confined to the sea, with 



Fig. 13. Morphology of Corynida. a. Fragment of Cordylophora lacustris, 

 slightly enlarged, b. Fragment of the same considerably enlarged, showing 

 a polypite and three gonophores in different stages of growth, the largest 

 containing ova. c. Portion of Syncoryne Sarsii with medusiform zob'ids 

 budding from between the tentacles. 



the single exception of Cordylophora, which inhabits fresh 

 water. In Tubularia and its allies the organism is protected 

 by a well- developed external chitinous envelope, or l poly- 

 pary ; ' but in the other genera belonging to the order the 

 polypary is either rudimentary, or is entirely absent. The 

 polypary of the Corynida, when present, is readily distinguished 

 from that of the Sertularida, by the fact that in the former it 

 extends only to the bavse of the polypites ; whereas in the 

 latter it expands to form little cups for the reception of the 

 polypites, these cups being called ' hydrothecse.' 



As regards the reproductive process in the Corynida, the 

 reproductive elements are developed in distinct buds or sacs, 

 which are external processes of the body- wall, and have been 

 aptly termed ' gonophores ' by Professor Allman. Great 

 variations exist in the form and development of these gene- 

 rative buds, and an examination of these leads us to some of 

 the most singular phenomena in the entire animal kingdom. In 

 some species of Hydractinia and Coryne, the generative buds or 



