68 



COMPARATIVE ANATOMY 



CHAP. 



Hydroid form. 



Sub-Order 2. 

 Tubularia. 



Small hydroid colonies, naked or 

 covered with a chitinous envelope (peri- 

 derm). The chitinous envelope never 

 widens into a cup (theca) round the polyp 

 head. In many forms the Medusce are 

 reduced to gonophores, which do not de- 

 tach themselves. 



Medusa form. 



Anthomedusae. 



Craspedote Medusce, without marginal 

 vesicles and otoliths, with ocelli at the 

 bases of the tentacles. Gonades in the 

 outer wall of the gastric peduncle ; 4, 

 seldom 6 or 8, radial canals. 



v Syncoryne Sarsii. 

 Podocoryne earned. 

 Eudendrium ramosum. 

 Bougainmllea ramosa (Fig. 62). 

 Stauridium cladonema. 

 Cordylophora lacustris \ 

 (in fresh water). J 

 Tubularia larynx. 

 Unknown. 



Examples. 



Sarsia tubulosa. 

 Dysmoi*phosa carnea. 



Lizusa octocilia. 



Margclis ramosa (Fig. 62, m). 



Cladonema radiatum. 



Wanting. 



Wanting. 

 Ctenaria ctenophora. 



Sub-Order 3. 



Campanaria. 



Small hydroid stocks with chitinous 

 periderm, which widens round the polyp- 

 head into a theca, into which the head 

 with the tentacles can be withdrawn. 

 The Medusa buds or sessile gonophores 

 generally arise united into groups in 

 special modified polyps devoid of ten- 

 tacles and mouth (gonangia). 



Leptomedusse. 



" Craspedote Medusce, some without, 

 some with, marginal vesicles, the latter 

 developed from the base of the velum 

 with ectodermal otolith cells. Ocelli at 

 the tentacle bases sometimes present, 

 sometimes wanting. Gonades always in 

 the course of the radial canals. Number 

 of radial canals various, often very great " 

 (Haeckel). 



Examples. 



Campanularia geniculata. 

 Unknown. 



Campanulina tenuis. 



Unknown. 



Unknown. 

 Laomedia Caliculata. 



The Plumularia and the Sertularia are 

 generally placed near the Campanaria. 

 These are elegantly branched Hydroid 

 stocks. In the first, the cups (thecrc) 

 which contain the nutritive polyps are in 

 a single row, in the second in two rows 

 on opposite sides of the stem. The sexual 

 products form bud-like outgrowths (gono- 

 phores), which generally arise in groups 

 on special modified polyps devoid of 



Obelia geniculata. 

 f Eucope campanulata. 

 1 (Fig. 65, p. 74.) 

 Phialidium variabile. 

 GastroUasta Raffadii. 

 Aequorea Forskalea. 

 Wanting. 



