HYDROIDS OF BEAUFORT, NORTH CAROLINA. 



381 



nematophores of the genus Plumularia. A mesial nematophore is present, situated on a process below 

 the hydrotheca. The hydrotheca is deeply campanulate. A single nematophore is found on each 

 stem intemode and one or two in each of the axils. 



Gonosome. — Unknown. 



Distribution. — On floating Sargassum off Bogue Bank. 



Genus PLUMULARIA. 



Trophosome. — Hydrocladium unbranched, pinnately arranged, 

 each having more than one hydrotheca; hydrothecEe with entire 

 margins; all nematophores movable. 



Gonosome. — Gonangia without extra protection. 



Key to the Species of Plumularia Found in the Beaufort 



Region. 



A. Hydrocladia arising from alternate intemodes only . P. alternata. 



B. Hydrothecae c)'lindrical, but slightly adnate P. floridana. 



C. Hydrocladia usually without intermediate internodes . P. inermis. 



D. Hydrocladial internodes with numerous internal ridges, 



P. setaceoides. 

 Plumularia alternata Nutting. 



Plumularia alUrnaia XuttitiK. Ajmerican Hydroids, pt. 1. igoo. p. 62. FiG. 48. — Plumularia alternata Nutting. 



Trophosome. — Colony attaining a height of about half an inch, simple, unbranched; stem genicu- 

 late, divided into intemodes, of which ever>' alternate one bears a hydrotheca and a hydrocladium. 

 This makes the hydrothecae more distant than usual. Hydrocladia divided into regular intemodes, 

 hydrothecate and nonhydrothecate alternating; hydrothecate intemodes boimdcd by oblique nodes 



proximally and transverse nodes distally; hydrothecae 

 deeply campanulate with about one-third of the distal 

 end free; supracalycine and mesial nematophores pres- 

 ent. There is one nematophore on each intemode, one 

 at tlie axil of the hydrocladium and one on each inter- 

 node of the stem. 



Gonosome. — Unknown. 



Distribution. — Found in abundance on floating Sar- 

 gassum and Turbinaria. 



Plumularia floridana Nutting. 



/'/«m«/(jriay7ori(/a«a Nutting. American Hydroids, pt. 1, 1900. p. 59. 



Trophosome. — Colony attaining a height of about half 

 an inch, simple, unbranched; stem divided into regular 

 intemodes, each of which gives rise to a hydrocladium 

 from a process at its distal end. There may be two or 

 three annulationsateach node. Hydrocladia divided into 

 alternate hydrothecate and nonhydrothecate intemodes, 

 FiG._49-P/«mu'ar«A'™/aM Nutting A, portion of jhe proximal being nonhydrothecate. Sometimes the in- 

 termediate intemodes may be again divided. Hydro- 

 thecae large, when the small size of the hydrocladia is 

 considered, nearly cylindrical, with sometimes more than the distal half free; nematophores small, supra- 

 calycine and mesial nematophores present, one on each of the intermediate but none on the proximal 

 intemode, one in the axil of each hydrocladium and one on each intemode of the stem. 

 Gonosome . — Unknown . 



Distribution. — On floating Sargassum off Bogue Bank, rare. 

 85079° — Bull. 30 — 12—25 



colony showing part of main stem; B, portion of 

 colony, more highly magnified. 



