HYDROIDS OF BEAUFORT, NORTH CAROLIXA. 



351 



they do in E. ramosum. I have never found any female gonophores arising from the hydrocaulus, as 

 they often occur in E. ramosum. E. ramosum and E. carneum are found growing side by side in so many 

 localities and have the general appearance so much alike that care must be taken to avoid confusion 

 between the two. 



Family HYDRACTINID.E. 



Trophosome. — Colon)- formed of distinct nutritive and generative zooids growing from a common 

 basal ccenosarc, which ordinarily is beset with jagged spines. Other kinds of zooids may also be present. 

 Hydranths with a single row of filiform tentacles; proboscis conical. 



Gonosome. — Gonophores in the form of fixed sporosacs on special generative zooids. 



Genus HYDRACTINIA. 



This is the only genus of the family. 

 Key to Species op Hvdr.\ctinia Found in the Beaufort Region. 



A. Generative zooids without tentacles, coenosiirc beset with jagged 



spines H. cchinata. 



B. Generative zooids possessing tentacles, jagged spines not present in 



the coenosarc H. carolincE. 



Hydractinia carolinse new species. 



Trophosome. — Colony composed of persons less crowded than in //. 

 echinata. arising from an encrusting mass which does not have the strongly 

 jagged spines, these being so much reduced as to be scarcely noticeable 

 as little nodules on the surface; hydranths much similar to those of H. 

 echinata. There were no dactylozooids present nor could any of the long, 

 slender, sensitive zooids be seen. 



Gonosome. — Gonophores borne on generative persons not ver)' much 

 unlike the nutritive persons, except that they are smaller and the tenta- 

 cles are somewhat less numerous. No batteries of nematocysts except 

 those ordinarily found on tentacles are present. In no case were there 

 more than two gonophores attached to one person. Six ova could be 

 made out in the majority of the sporosacs. 



Color.— As the specimens had been in alcohol for a long time, naturally no ver>- definite color could 

 be made out. 



Distribution.— Found growing on the legs of a crab dredged by the United States Fisheries steamer 

 Fish Hawk about 23 miles southwest of Beaufort, in 13 or 14 fathoms of water. 



This species differs from other species of Hydractinia in the nature of the gonosome, in the absence 

 of other than the nutritive and generative zooids, and in the absence of pronounced spines on the basal 

 expansion. 



As all the specimens obtained were from the legs of an individual crab, the zooids were all of one 

 sex, female. The presence of several tentacles and the absence of special batteries of nematocysts 

 readily distinguish it from almost all other species. The number and arrangement of the gonophores 

 are distinctive, but these var>' with different species. The absence of the dactylozooids and of the 

 basal spines may be due to the same cause. There is not much necessity of these, as the surface of the 

 crab's legs is well protected, in the first place, by large, sharp spines, and, in the second, in some places 

 at least, with a regular thicket of stiff bristles. These must offer as good protection as is afforded in 

 other species by the special protective persons. 



The fact that the long, slender, sensitive persons were not observed does not necessarily indicate 

 their absence, as it is seldom that they can be observed, except when they are in the active state in 

 live colonies, and even then they are not xery numerous. 



Fig. 9- — Hydractinia carotitur, new 

 species. -\ and B.nutritivezooids; 

 C, generative zooid. 



