TUBULARIAE. 129 



ring of dactylozooids. The cavities of the zooids communicate with 

 the coenosarcal meshwork by large canal offsets. Gonophores having 

 the form of rudimentary medusae are developed on the coenosarcal 

 tubes, and are often lodged in special ampullae of the coenoat^um. 

 The tentacles generally possess knobbed extremities armed with 

 thread cells. From coral reefs and warm seas. 



Fam. 1. Milleporidae. Coenosteum arborescent or encrusting, composed of 

 a thin superficial living layer, lying upon dead layers of former growth. Pores 

 without styles, but divided by tabulae marking the successive layers of growth. 

 Dactylozooids with knobbed tentacles. Millepora L. 



Fain. 2. Stylasteridae. Coenosteum arborescent, with a strong tendency to 

 assume a fan-like form, and to the development of the pores on one face only 

 or on the lateral margins of its branches. In some genera a superficial layer 

 only of the coenosteum is living, in others nearly the entire mass retains its 

 vitality. Pores with tabulae in two genera only. Gastropores provided with 

 a conical calcareous projection the style at their bases. Pseudosepta, arising 

 from the partial confluence of the dactylopores and gastropores, sometimes 

 present. Dactylozooids without tentacles. Colonies dioecious. Found in all 

 seas in shallow and deep waters. 



Sporadopora Moseley ; Pliobothrus Pourtales ; Errina Cray ; Distichopora 

 Lamarck ; Labiopora Moseley ; Spinipora Moseley ; Allopora Ehrenberg ; 

 Stylaster Gray ; Stenohelia S. Kent ; Conopora Moseley ; Astylus Moseley ; 

 Cryptohelia M. Edw. and Haime. 



Order 3. TUBULARIAE* (GYMNOBLASTEA). 



Without hydrothecae and gonangia. Polyps, ivhen more than one, 

 forming permanent colonies. Generative individuals, ivhen set free, 

 are Anthomedusae. 



The Tubulariae are almost all colonial (the Corymorphinae, Myrio- 

 thela, etc., are solitary), and they all produce medusoid gonophores 

 by budding. The gonophores are either set free as Medusae, or 

 only become partially developed as medusoids, with rudiments of the 

 medusan organs, e.g., manubrium, gastro vascular canals, and marginal 

 tentacles. The Medusae have ocelli, and their gonads are in the 



manubrium. 



Section 1. Tubularinae. 



Colonial forms with a perisark destitute of investing layer of coenosark. 



Fam. 1. Clavidae. Polyps with scattered filiform tentacles. Clava Gmelin ; 

 Cordylophora Allm., fresh and brackish water; Tubidava Allrn. ; Merona 

 Norman ; Rhizogeton Ag. ; Clavula Wright ; Dendrodava "Weissman ; Campani- 

 dava Allm. ; Corydendrium v. Ben. 



* G. J. Alhnan, A Monograph of the Gymnoblastic or Tubularian Hydroids, 

 Ray Society, 1871. G. J. Allman, "Report on the Hydroidea," Pts. 1 and 2 

 Challenger Reports, 1883 and 1888. T. Hincks, A Monograph of the British 

 Hydroid Zoophytes, London, 1868. E. Haeckel, Monographic der Medusen, 

 Jena, 1879. 



