SPONGES, ZOOPHYTES, AND SEA-FIRS. 61 



CCELENTERA. Hollow-bodied animals with tentacles and sting- 

 ing-cells. 



Class I. HYDROZOA. 



Sub-class. HYDROMEDUS^;. 



Order I. GYMNOBLASTEA. Zoophyte colonies in which the horny 

 investment, if present, does not form cups for the zooids. 



Tentacles scattered and 



Tentacles thread-like. 



very numerous. J ava " 



Tentacle in two circles. Tulularia. 

 Tentacles in one circle. 



. ^ 



Zooids not all similar. ) 



{Colonies produce sessile \ 

 sporosacs. / oryne 



Colonies produce free ^ 

 medusoids (Sarria). ) 



CHARACTERS OF SPECIES. 



Clava. Two common species, C. squamata forming dense clusters on 

 weed, C. multicornis with scattered individuals usually on 

 stones. 



Coryne. A common species is C. piisilla, a small, rather delicate 

 species, with slightly branched stems marked with rings. 

 Tentacles, about thirty, in many circles ; zooid long and 

 slender, scarcely tapering below. 



Syncoryne. A common and conspicuous species is S. eximia which 

 forms bushy tufts on weeds. Stems often several inches in 

 length, smooth save for a few annuli at the base, profusely 

 branched. 



Tubularia. In T. indivisa the stems are long, unbranched, and 

 smooth. Between the upper and lower circle of tentacles are 

 inserted the grape -like bunches of sporosacs. 



Hydradinia. In H. echinata the colony forms a pinkish crust on 

 shells inhabited by hermit-crabs. For description see text. 



Order II. CALYPTOBLASTEA. Sea-firs, in which the zooids are 

 placed in horny cups. 



CHARACTERS OF FAMILIES. 



Fam. Campanularidee. ( Cly * ia > Obelia, Campanularia are not dis- 



Cups bell-shaped and \ tin g sh ed by any peculiarity of the 



stalked colonies as a whole, but only by their 



I reproductive persons (see pp. 50-52, 60). 



Fam. Campanulinidfe. } 7 n W.LI. j- , 



Cups ovate and coni- Opercularella. With a distinct operculum 

 calf stalked. J (ee below). 



