68 AMERICAN HYUROIDS. 



This species is squarely intermediate between the genera Thuiaria and Sertularella, having 

 the characters of numerous hydrotheca? to the iuternode, and the two-toothed margin and two- 

 valved operculum of the former, and the exactly alternate hydrotheca? of the latter. I place 

 it provisionally in the latter genus, as it seems here to find, on the whole, its closest affinities, 

 although it agrees quite well with St-rtnlorillo nana Hartlaub, so far as the nonspecific characters 

 are concerned. 



.'THUIARIA RAMOSISSIMA Allman. 

 Thuiai-iii riniiimixxiiiKt ALLMAN, Gatty Coll., 1S85, p. 146. 



^Ti'njiltnxiiiiK'. Hydrocaulus monosyphonic, main stem sending off in every direction 

 branches which are themselves profusely branched; ramifications subdichotomous. each bifurca- 

 tion preceded by a transverse joint. Hydrothecre alternate, adnate to the hydrocaulus by the 

 whole of their epicauline walls, deep, tubular; the apocauline margin of aperture deeply cleft. 



" (jfiniiixiinii; Gonangia springing each from a point placed laterally just below the base of a 

 hydrotheca. None mature in the specimen. 



"Locality. Northeast coast of America." 



I have not seen this species and have copied the above description entire. It resembles 

 greatly the common Tliniorlo or</i nt,o, but it does not seem likely that Professor Allman would 

 have made a mistake regarding such a well-known form. 



THUIARIA DIFFUSA (Allman). 

 (Plate X, figs. 1-3.) 



Sertularel/ii il'iffnsu ALLMAN, Gatty Coll., 1885, p. 136. 



var. MARKTANNER-TURNERETSCHER, Hydroiden des k. k. naturhist. Hofmuseums, 1890, p. 229. 



TropJiosome. Colony attaining a height of !> inches (Allman), much branched, stiff, and 

 corneous in aspect. Stem nearly straight, divided into long and irregular internodes, lower part 

 without hydrothecae. Branches straight, alternate, themselves dividing alternately and the 

 branchlets ultimately dividing dichotomously, divided into usually long internodes of unequal 

 length, the distal being generally the shorter. IIydrothee;e tubular, gracefully curved, ordinarily 

 strictly alternate, about the distal half free and pointing forward and outward, margin with two 

 large pointed lateral teeth, aperture crescent-shaped. Operculum not evident, the distal superior 

 part of the hydrothecal wall being very thin and collapsible so that it seems to serve as an 

 operculum. 



<iiiiiiiKiniii . Gonangia borne, on distal part of the branches, ovoid, with two lateral anterior 

 spines and a narrow collar surrounding a broad, round aperture. 



Distribution. Rockaway (Atlantic coast, U. S. t) (Allman). South America (Marktanner- 

 Turneretscher); "South America," specimen from Levinsen; Allot m. Station 2:i7!.i, lat. N. 

 35 20' 55", long. W. 75 20' 55", 16 fathoms. 



This species also is very near Tliuiaria argentea, and the specimen described by Allman may 

 belong to this species. Those described by Marktanner-Turneretscher, the one from Station 

 2279, and the specimen sent me by Professor Levinsen from South America seem to be specifi- 

 cally distinct. The whole texture is stiff and rigid and deeply corneous in color, differing greatly 

 from T. unii Htm. The forming of a pseudo-operculum by the thin collapsible distal part of the 

 inner (upper in position) hydrothecal wall is an interesting feature. 



THUIARIA DALLI, new name. 



(Plate X, figs. 4-6.) 



Srrl,il,iri<i i-ii/in-isxiiiilfx ( 'I.AKK, Alaskan Ilydmids, ISTfi, p. 220. 



riii i-iijii-i'ii!ili-it 'XfTTiNt;, Hydroids of the Harrinian Expedition, 1901, p. 185. 



. Colony small, in specimens examined, and plumose in form. Main stem 

 straight, divided into usually short internodes by oblique nodes, many internodes bearing two 



1 Name preoccupied by Kirrhenpauer, Nordische Gattungen und Arten, 1884, p. 18, for an entirely different 

 species. 



