396 D'ARCY W. THOMPSON, HYDROIDA. 
Thuiaria turgida, 5. F. Clarke. 
PIE AN 
This Alaskan species, which was one of the most abundant 
in Clarke's collection, is represented in the Vega collection 
by: & single example from 422 30- EB. long, 
T. turgida is a very distinet species, conspicuous for its 
stout habit, and close, thick-set, opposite hydrothece. The 
latter measure 0,5 mm. in length. It belongs to the samer 
vision of the genus as T. articulata, resembling it in its regular 
pinnate habit, and the plain circular orifice of the hydrotheca. 
No natural size drawings of this or the following species 
of Thuwiaria have yet been published, and I accordingly present 
figures of them all. 
The three following species of Thuiaria are closely allied. 
They belong to the group of plumose species with bilabiate 
hydrothec&e, which seem to be especially abundant in the 
Alaskan region. There the group is represented by T. robusta, 
S. F. C., T. plumosa, S. F. C., and by T. (Sertularia) cupressoides, 
and similis, S. F. C.1 Our T. (S.) cupressina and argentea, A11- 
man's T. ramosissima (which must be very similar indeed to 
T. plumosa), from N. E. America (Journ. Linn Soc) föcsomp 
146), and T. Vege, n. sp., from the present collection, arevtne 
remaining forms ascribable to the group. 
Thuiaria plumosa, S. F. Clarke. 
PI:E1862e TSE 2 OR 
The Vega collection contains specimens of this species 
from the station in long. L74A 20 E. 
It is a large and handsome species, the older specimens 
having their upper branches thinned away, and tapering up- 
wards to a pointed apex, much as in old specimens ortieCs 
cupressina. But the branches are longer, and the hydrothecee 
larger than in the latter species, and the extensive space of 
bare stem in the lower portion of the zoophyte is a feature 
not shared by the other. An exaggeration of the same feature, 
combined with a stiffer but at bottom quite similar mode of 
branching, would lead us directly to the peculiar habit of 
T. thuja. 
1 These species, ascribed by Clarke to Sertularia, are, as Allman has 
remarked of S. cupressina and argentea, true Thuiarie. (Journ. Linn. Soc., 
UI, SAML 10 AI 
