226 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



Locality. — Dredging station 5165, Sulu Archipelago, Tawi Tawi 

 group, Observation Island, 4° 58' 20" N., 119° 50' 30" E. ; depth, 

 9 fathoms. 



Holotype.— Cat. No. 42181, U.S.N.M. 



This species is evidently nearest P. dendritica Nutting, 23 which 

 it resembles greatly in the form of the hydrothecae and in general 

 appearance. It differs, however, in having much more distant 

 hydrothecae, in the absence of regular hydrocladial internodes and in 

 the very strong internal ridges in the hydrocladia. Although the 

 two species are found in the same general region, the specimens 

 differ constantly in the points just mentioned and the writer feels that 

 they should be regarded as distinct species. Indeed, they are fully 

 as distinct as many other species of Plumularia and Aglaophenia 

 which have been recognized. This species also resembles Plumularia 

 asymmetrica Bale 2i particularly in the general shape of hydrothecae, 

 the internal hydrocladial ridges and the nematophores. It differs 

 materially in not having the anterior intrathecal ridge and in not 

 having the two sides of the hydrothecae unsymmetrical as described 

 by Bale. 



ANTENNELLA BIARMATA, new species 



Plate 44, fig. 5 



Trophosome. — Colony consisting of a number of upright hj^dro- 

 cladia springing directly from a creeping root-stalk and attaining a 

 height of about 3 cm. Proximal part of hydrocladia devoid of 

 hydrothecae but often bearing a double row of nematophores on one 

 side, there being sometimes as many as 16 pairs of nematophores 

 below the first hydrotheca. Nodes oblique, not regularly disposed, 

 but with a tendency to showing two hydrothecae to each internode. 

 Often there is a very pronounced oblique node about the middle of 

 the hydrocladium. Hydrothecae stiffer and more dense than in 

 other species of this genus that I have seen, closely approximated, 

 being separated by less than their own height, cylindrical, deeper 

 than most of the genus, one and one-half times as deep as wide; 

 margin even, distinctly everted so that the actual aperture is much 

 greater than a section below the margin. About one-fifth of the 

 distal part of the hydrotheca is free from the hydrocladium which 

 bears it. Nematophores — there are two pairs of supracalycine 

 nematophores, one borne on a long rodlike support springing from 

 the hydrocladium almost opposite the middle of the hydrotheca and 

 extending outward and a little upward nearer to the hydrothecal 

 margin, so that the nematophore itself projects beyond the front of 

 the hydrotheca but considerably below the aperture. Immediately 



s» American Hydroids, pt. 1, 1900, p. 67, pi. 8, figs. 4-6. 



24 Report on the Hydroids collected in the Great Australian Bight, etc., 1914, p. 29, 

 pi. 4, figs. 2 and 3. 



