II cm D ARIA— LITERATURE 117 



morphosis. Development with alternation of generations and without 

 it can occur in the same species. 



In Comls a free-swimming larva is produced from the fertilised 

 egg, and this attaches itself and develops into a Coral, which either 

 remains a single individual or produces a Coral -stock by means of 

 gemmation and incomplete fission. 



The Ctenophffra, without exception, develop direct. 



From the fertilised egg of the Siphonophora a medusoid organism 

 arises, which, by budding, yields the polymorphic animal stock. Here 

 also {Physalia, Disconanthe) the medusoid gonophores can detach them- 

 selves from the stock and lead a free life as sexual individuals. In 

 many SiphoTianthe groups of persons, the already mentioned Eudoxim 

 and ErscecB, detach themselves from the stock, and swim about freely 

 as minute new animal stocks. In their gonophores the sexual pro- 

 ducts are developed. From the fertilised egg a medusoid organism 

 arises, which by gemmation again becomes the polymorphic animal 

 stock. We thus have here again to do with a sort of alternation of 

 generations. 



Literature. 



E. Leuokart. Zoologische Untersuchmigen I. Giessen, 1853. 



The same. Ziir ndhern Kenntniss der SiphonopJioren von Nizsa. Arch. f. 



Naturgeschiclde. 1854. 

 C. Gegenbaur. BeohacMungen iiher Svphonoplioren. Zeitschr. f. to. Zool. 1853. 

 The same. Neue Beitrage ziir Kenntniss der SipAonophoren. Nova ada. Tom. 27. 



1859. 

 C. Vog^. Memoires sur les SiphonopTiores. Memdres de I'Institut genevois. 1854. 

 A v. Kolliker. Die Siphonophoren oder Schwimmpolypen von Messina. Leipzig, 



1853. 

 Milne-Edwards et J. Halme. Sistoire naturelle des CoralUaires. 3 vols. Paris, 



1857-60. 

 Th. Huxley. The Oceanic Hydrozoa. Roy. Society. London, 1859. 

 De Lacaze-Duthiers. Bistaire naturelle du corail. Paris, 1864. 

 Th. Hincks. Natural History of the British Eydroid Zoophytes. 2 vols. London, 



1868. 

 Kolliker. AntomiscTi-systematische Beschreibung der AUyonarien. Die Pennatiilidcn. 



Abhandlungen Senkenb. nat. Ges. Frankfurt. Bd. 7 and 8. 1872. 

 C. Claus. Ueber Salistemma tergestinum. Arbeit. Zool. Institut. Wien. 1878. 

 G. J. AUman. A Monograph of the Gymnoblastic or Tiibularian Sydroids. London, 



1871-72. 2 vols. 

 N. Kleinenberg. Hydra. Leipzig, 1872. 

 0. and E. Hertwig. Das Nervensystem und die Sinnesorgane der Medusen. Leipzig, 



1878. 

 The same. Die Actinien. Jen. Zeitschr. f. Natitrwiss. Bd. XIIL u. XIV. 1879-80. 

 E. Hertwig. Ueber den Bau der Ctenophoren. Jena, 1880. 

 C. Chun. Monographic der Ctenophoren. In: Fauna und Flora des Golfes von 



Neapel. Leipzig, 1880. 

 E. Haeckel. System der Medusen. Jena, 1880, 1881. 

 A. Andres. Monografia delle Attinie. 1. Theil. In : Fauna und Flora des Golfes 



von Neapel. 1884. 



