OF THE 'POKCUPIXE' EXPEDITIONS. 473 



This species has a peculiar habit, caused by its long, rather distantly disposed, flexile 

 branches, which give it a loose diffuse character, by which it contrasts with the closer 

 and more compact habit of other species. 



It was obtained from the cold area lying between Shetland and the Faroe Isles, m two 

 dredgings — one at 640 fathoms, where the bottom had a temperature of 30° Fahr., and 

 the other at 363 fathoms, with a bottom-temperature of 30°-6 Fahr. 



Thuiaeia hipptjkis. Plate LXV. figs. 2, 2". 



Troplwsome. — Stem attaining a height of about six inches, slightly zig-zag, except 

 towards its base; its proximal end for about one sixth of its entire length destitute 

 of branches, annulated irregularly at the base, and with joint-like annuli at irregular 

 intervals for some distance upwards ; branches repeatedly dividing dichotomously so as 

 to form fan-shaped groups. Hydrothecae on the main stem scattered, on the branches 

 alternate ; those in each series separated from one another by a distance of little more than 

 two thirds of their height ; orifice semicircular, pro\ided with a valve-like operculum. 



Gonosome not known. 



Thuiaria hippuris has somewhat the aspect of T. thuia, from which, however, it differs 

 by its less crowded ramuli and more distant hydrothecee, as well as by its more attenuated 

 and flexile stem. 



It was dredged in the deep cold area between Shetland and the Faroe Isles, along with 

 Thuiaria laxa, from a depth of 640 fathoms, where the temperature of the bottom was 

 as low as 30° Fahr. 



Thuiaeia salicoenia. Plate LXV. figs. 3, 3". 



Trophosome. — Stem attaining a height of about two inches, jointed at rather u-re- 

 gular intei-vals, simple or sparmgly branched, somewhat rigid, with pinnately disposed 

 branchlets above, destitute of branchlets below; pinnae alternate, about four lines 

 in length, articulated to projections of the stem. Hydrothecs flask-shaped, alternate, 

 immersed for the greater part of their depth, but becoming free at a short distance 

 from the orifice, simply distichous on the main stem, and with the axes of all the 

 hydrothecffi in each row turned in the same direction, but on the pinns having their 

 axes alternately directed to the right and left, so as to give them here an apparently 

 tetrastichous arrangement. 



Gonosome not known. 



The alternating directions of the axes of the hydi-otheca; composing each row of the 

 pinnae confer on this species a striking physiognomy. T. salicornia further differs from 

 other species of Thuiaria in the less complete immersion of the hydrothec^, and from 

 most species in its simple pinnately disposed ramuli. It was obtained west of the Faroe 

 Isles, in lat. 62°, long. 5° 30', at a depth of 114 fathoms. 



