[187] THE HYDROIDS 205 



THUIARIA ELEGANS sp. nov. 

 (Plate XXV, figs. 1-3.) 



Trofhosome. — 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, vvrith 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.) 



Trofhosome. — 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. 



