HYDROIDS OF THE WOODS HOLE REGION. 



368 



Sertularella gayi (Lanix.)- Fig. 64. 

 i Xri-tiilnriu i/iii/i Lamx., Kxpositicjn Methodique, p. 12.) 



Ti-n/iliiixoiiie. Like the last, lint much more robust. Branches regularly pinnate and approximate. 

 Hydrothecse much larger, often corrugated on the upper side. 



tliiiKHSiiiitr. Gonangia with a 2-toothed aperture. 



Digtrihittlon.A. specimen in the 1 T . S. Fish Commission collection at Woods Hole bears the label 

 "E. by S., Sankety Light, Nantiicket, i"> fath." This specimen has much larger and coarser hydro- 

 thecw than specimens from Kngland, and may represent a distinct species. 



62. Sfrtularella rugosn (Linn.). 63. tyrtnltirclla jioli/:onias (Linn.). 

 THUIAEIA. 



64. Sertularrtkt <jni/i (Linn.). 



Trophwonif. Colony branched; stem and branches divided into 

 internodes each of which bears more than two opposite or subopposite 

 hydrotheae which are usually deeply immersed in the stem. Hydro- 

 thecse tubular, or flask-shaped, with bilabiate apertures. 



Gonosome. Gonangia much like those of Sertularia. 



Key to species of Thuiaria found in the Woods Hole region. 



A. Stem long and slender, bearing slender branches which subdivide dicholomously. 

 Gonangia bimucronate. 



a. Hydrothecse free for about their distal one-third T.argentea. 



a'. Hydrothecse immersed almost to the orifice T. cupressina, 



A". Stem a'nd branches rigid, the latter stiff and subverticillately arranged. Gonangia 

 without mucronate processes on end T. thuja. 



Thuiaria argentea (Ellis & Solander). Fig. 65. 

 i&'ilularia argentm Zooph., p. 38.) 



Trophoeome, Colony breaking up basally into long, slender main 

 branches which give off spirally set, closely approximated secondary 

 branches which branch dichotomously, each forming a graceful flabellate 

 structure; internodes rather slender, each bearing a group of several 

 hydrothecse. Hydrotherae subalternate, tubular, their distal ends curv- 

 ing gently outward, so that about the terminal one-third is free; aperture 

 armed with two opposite teeth, one much longer than the other. 



Gonosome. Gonangia with two lateral projections and a central 

 terminal orifice. 



Distribution. Vineyard Sound, Long Island Sound, and other parts 

 of the coast, Very common in depths from 1 to 20 fathoms. 



65. Thuinria argentea (Ell. 

 A. Gonangium. 



