104 



CCELENTEEATA 



Fig. 171 'Tubularla crocea (Agassiz). 

 B, a single hydranth. 



B 



A, a colony 



T. (Parypha Ag.) 

 crocea (Ag.) (Fig. 171). 

 Colonies growing in dense 

 tufts of long tangled 

 stems of from 8 to 10 cm. 

 in height ; sparingly 

 branched ; basal tentacles 

 20 to 24; apical process of 

 the female sporosac flat- 

 tened: common on piles, 

 docks, etc., in shallow 

 water from Boston south- 

 wards; California, 



ORDER 4. CAMPANULARIAE.* (CALYPTOBLASTEA; LEPTOMEDUSAE. ) 



Colonial hydromedusans with two kinds of polyps (Fig. 172), the 

 hydranths or the nutritutive polyps and the blastostyles or the reproduc- 

 tive polyps. The perisarc does not end at the base of the polyp, as in 

 the tubularians, but continues over it, forming, in the case of the 



hydranth a protective cup called the hydro- 



theca and in the case of the blastostyle a 



cylindrical capsule called a gonangium or a 



gonotheca. In some species the open end of 



the hydrotheca may be closed by projections 



or valves which form an operculum (Fig. 



173); in some species also the blastostyle 



projects out of the mouth of the gonangium 



and forms a large cap- 



sule or brood chamber 



in which the eggs de- 



velop, called the aero- 



cyst (Fig. 178). The 



hydranth has never 



more than a single 



whorl of tentacles and 



can in most cases be 



retracted within its 



hydrotheca or extended 

 beyond it. The blastostyle cannot usually be extended beyond its 

 gonangium and produces within it the gonophores; these constitute 



Fig. 172 A campanularian 

 hydroid (from Hegner). 1, 

 hydranth ; 2, hydrotheca ; 3, 

 blastostyle ; 4, gonangium. 



Campanularian oper- 

 cula (Nutting). A, 



two-valved operculum ; 



B, one-valved opercu- 

 lum. 



* See "The Leptomedusae of the San Diego Region," by H. B. Torrey, Uni. of 

 Cal. Pub., Vol. 6, p. 11. 



