TUBULARIAE 99 



Key to the species of Eudenriidae here described: 



Oi Colony large (8 to 15 cm, high). 



6i Branches annulated at their base only E. bamosum 



&2 Branches completely annulated E. DISPAR 



O2 Colony small (less than 3 cm. long) E. tenue 



E. ramosum (L.) (Figs. 150 and 161). Colony profusely branched, 

 10 to 15 cm. high, with symmetrical branches; tentacles about 20; male 

 sporosacs reddish and in moniliform clusters; female sporosacs orange 

 and pyriform: abundant on piles, rocks, etc., in shallow water from 

 North Carolina to Labrador; Pacific Coast; Europe. 



E. dispar Agassiz. Colony less profusely branched than above, 



Fig. 161 Fig. 162 



Fig. 161 — Eudendrium ramosum (from Hargitt). Fig. 162 — Hydractinia echinata 



(McMurrich) . 1, feeding hydranth ; 2, defensive 



hydranth ; 3, reproductive hydranth. 



6 to 10 cm. high; tentacles about 28; sexes distinct: in deeper water 

 from Vineyard Sound to Bay of Fundy. 



E. tenue A. Agassiz. Colony irreg-ularly branched, 25 mm. in height; 

 male sporosacs moniliform and pink; female sporosacs orange and scat- 

 tered over the hydrocaulus: on seaweed, etc., in shallow water from 

 Buzzard ^s Bay to Bay of Fundy; not abundant. 



Family 5. HYDKACTINIIDAE. 



Trophosome: colony incrusting, the polyps rising separately from 

 an incrusted, spiny hydrorhiza to which the perisarc is confined, and 

 polymorphic, consisting of 3 types of individuals: (1) feeding hydranths, 

 which have a single whorl of tentacles; (2) reproductive individuals, 

 bearing clusters of sporosacs; and (3) defensive individuals usually 

 Avithout tentacles but with numerous nematocysts at the apex. Gono- 

 some: sporosacs and no free medusae present: 1 genus. 



