[187] THE HYDROIDS 20$ 



THUIARIA ELEGANS sp. nov. 

 (Plate xxv, figs. 1-3.) 



Trophosome. Colony consisting of a central nonfascicled stem 

 branching in a plumose manner and attaining a height of about six 

 inches. Stem bearing hydrothecae throughout its length, divided by 

 oblique nodes into long and irregular internodes, each of which usually 

 bears three or four branches ; branches alternate, pinnately arranged, 

 unbranched proximally, and distally dividing into a number of branch- 

 lets ; internodes of stem irregular, but each bearing normally more 

 than one pair of hydrothecae. Hydrothecae subalternate, short, pitcher- 

 shaped, with a double curve in front and an even aperture much like 

 the top of a pitcher ; operculum composed of a single flap. 



Gonosome. Gonophores borne on the upper sides of the distal ends 

 of the branches in a closely set double row. The individual gonangium 

 is slender, oblong-oval, with a truncated top, an internal distal plug 

 which appears as a dark collar, and an internal mass of developing sex 

 elements. 



Distribution. Berg Inlet, Glacier Bay, 20 fathoms ; Dutch Har- 

 bor, Alaska (Harriman Exped.). 



THUIARIA COSTATA sp. nov. 

 (Plate xxvi, figs. 4-9.) 



Trophosome. Colony usually a single stem giving forth alternate 

 branches, the whole having a plumose appearance, stem simple, 

 straight, the lower part composed of regular internodes, each bearing a 

 pair of subopposite hydrothecae, the upper part divided into regular 

 internodes, each bearing a branch and three hydrothecae ; nodes 

 oblique. Branches alternate and themselves branching dichotomously, 

 divided into unequal internodes, each bearing more than two suboppo- 

 site hydrothecae. Hydrothecae turgid below and narrowing above into 

 a short neck which ends in a round aperture facing upward. A chiti- 

 nous spine projects downward from the lower inner side of each hy- 

 drotheca. 



Gonosome. Gonangia borne profusely on both faces of the stem 

 and often on the proximal ends of the branches ; oblong-ovate, with a 

 short, small neck and round terminal aperture, the gonangia are orna- 

 mented with about five compressed longitudinal ridges, the crests of 

 which are colored black. General color of the gonangia orange brown. 



Distribution. Yakutat, Alaska. Abundant (Harriman Exped.). 



This species resembles Sertularia inconstans Clark, but differs 

 considerably, particularly in its gonosome, which is very strongly 

 marked. 



