110 CCELENTEBATA 



S. gracillima (G. 0. Sars) (Fig. 181). Colony about 5 cm. high; 

 branches divided into regular internodes, each bearing a hydrocladium : 

 New England coast; Europe. 



4. Cladocarpus Allman. Colony usually branched; hydrocladia 

 not branched ; gonangia borne on the stem at the base of the hydrocladia 

 and protected by special branchlets armed with nematophores : 15 

 American species. 



C. flexilis Verrill (Fig. 182). Colony up to 20 cm. long and slender; 

 hydrotheca long and cylindrical, lying close to the hydrocladium; pro- 

 tecting branchlets of the gonangia branched like deer's horns: in moder- 

 ately deep water along the Atlantic coast; common. 



Family 3. CAMPANULAEIIDAE. 



Trophosome: either a branched or simple colony on which are bell- 

 shaped and usually stalked hydrothecae; hypostome trumpet-shaped. 

 Gonosome: gonangium large, the blastostyle producing planulae and 

 never free medusae: about 33 genera. 



Key to the genera of Campanulariidae here described: 



a- Hydrotheca rudimentary, the hydranth not being entirely retracted 



into it 1. Halecium 



ajHydrotheca not rudimentary, 

 fei Blastostyle does not project from the gonangium. 

 Ci Stem not completely annulated. 



di Gonangium without aeroeyst, colony not parasitic 2. Campanulabia 



dj Gonangium with aeroeyst ; colony parasitic on other hydroids, etc. 



3. Calycella 



Cj Stem completely annulated 4. Opercularella 



62 Blastostyle projects from the gonangium 5. Gonothyrea 



1. Halecittm Oken. Branching colonies with creeping hydrorhiza; 

 the hj^drothecae are more or less rudimentary, being shallow and 

 disc-like or funnel-shaped, the margin often with a circle of dots, 

 into which the hydranths can be only partially retracted: numerous 

 species. 



H. halecinum (L.) (Fig. 183). Colony 10 to 20 cm. high, rigid; 

 hydrothecae alternate on the stem, cylindrical, often annulated; gonan- 

 gia appear in a row, the male gonangium slender and club-shaped, the 

 female rather irregular in shape with broad distal end and a terminal 

 aperture: New Jersey to Labrador; in shallow water; Puget Sound to 

 Alaska; Europe. 



2. Campanularia Lamouroux. Colony either branched or simple, 

 with bell-shaped hydrothecae, which are without operculum, and with 

 or without marginal teeth; many species. 



