112 



CCELENTERATA 



with untoothed aperture and with annulated stalks; gonangia large: 

 Long Island Sound to Labrador, on piles, etc., abundant towards the 

 north; Europe. 



3. Calycella Ilineks. Hydrorhiza parasitic on other hydroids, 

 Bryozoa, etc., and sending forth short annulated stalks bearing elongate 

 cylindrical hydrothecae which have opercula; gonangium oval, rising 

 from the hydrorhiza and bearing a globular acrocyst. 



C. syringa (L.). Hydrotheca longer than 

 its stalk: Long Island sound to Maine; com- 

 mon; PaciKc coast; Europe. 



4. Opercularella Hincks. Stem annu- 

 lated throughout and sparsely branched or 

 unbranched; hydrotheca with operculum; 

 gonangium with acrocyst. 



0. lacerata Hincks. Hydrothecae with 

 short stalks; segments of operculum very long 

 and slender: Long Island Sound to Maine, on 

 docks, etc. 



5. GoNOTHYREA Allman. Stem erect, ir- 

 regularly branched, more or less annulated; 

 hydrotheca bell-shaped, with toothed margin; 

 the blastostyle produces fixed, medusiforni 

 sporosacs with radial canals and tentacles, which 

 project out of the gonangia but are not free- 

 swimming: several species. 



G. loveni Allman (Fig. 186). Stem 10 to 

 15 mm. high; from the mature gonangium project 3 to 5 sporosacs: on 

 shells, stones, etc., in shallow water from Long Island Sound to Maine; 

 Europe. 



G. clarki Torrey. Similar to the above but without radial canals in 

 the sporosacs; hydrotheca deep, with margin having 10 square-topped or 

 bicuspid teeth : Pacific Coast from California to Alaska ; often common 

 in shallow water. 



Fig. 186 — Gonothyrea 

 loteni (Hargitt). 



Family 4. EUCOPIDAE. 



Trophosome: colonial, either branched or simple; hydrotheca bell- 

 shaped and stalked, the margin of the aperture either toothed or not; 

 gonangia large and usually in the axils of the branches. Gonosome: 

 gonangium large, the blastostyle producing free medusae with lithocysts 

 and usually without ocelli, with 4 radial canals, beneath which on the 

 subumbrella are the gonads, there being as many gonads as radial 

 canals: about 34 genera. 



