ON THE HYDROIDS OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 19 



being in the same line as the adnate, the whole axis lying practically parallel to the 

 stem. The margins of the hydro thecal are divided into three teeth, a small one on the 

 adcauline edge, and two large and equal ones on the margin remote from the stem. 

 The number of flaps in the operculum could not be counted. 



Gonosome. — Not present. 



Locality, etc. — Growing on Staurotheca reticulata, Scotia Bay, South Orkneys. 

 Depth, 65 fathoms. Date, 25th March 1903. 



Thujaria pectinata, AUman, 1888. 



A single specimen some 6 cm. high almost completely enveloped in a dense polyzoon 

 growth. The stem is unbranched and monosiphonic about 1 mm. across, and is divided 

 into equal internodes, each of which bears three pairs of opposite hydrothecse. A pair 

 of opposite pinnse arise from each internode, originating between the proximal and 

 median pairs of hydrothecse. On the pinnse the nodes are quite distinct, being marked 

 by a constriction (in Allman's figure they are scarcely indicated), and the hydrothecse 

 are arranged as on the stem — three pairs to each internode. The hydrothecse are so 

 closely approximated that the top of one touches the base of the next, but the " free 

 membranaceous extension of the wall " has in every case been destroyed, leaving a rather 

 ragged edge level with the general outline of the pinna. One of the pinnae, instead of 

 being thecate to the tip, was produced into a long, tubular, tendril-like process. 



Gonosome. — Not present. 



Locality. — Dredged at the entrance of Saldanha Bay, Cape Colony, in 25 fathoms. 

 Date, 21st May 1904. 



Spithecium robustum, Nutting, 1904. (PI. I. fig. 6.) 



About half-a-dozen specimens of this species have been dredged from the locality 

 of Burdwood Bank. The average height is about 7 cm., but two specimens are 11 cm. 

 high by 4 cm. broad, almost twice the size of the specimen described by Nutting. 

 The branches, which are regularly opposite, are simple in the majority of the 

 specimens, but in some they rarely bear opposite branchlets ; and not only in these 

 branchlets, but even in the branches themselves, there is a distinct narrowing of the 

 perisarc immediately above each pair of hydrothecae. The hydrothecae have frequently 

 one or two annular striations — lines of reduplication — round their margins. Except in 

 these details the trophosome agrees with Nutting's description. 



Gonosome. — The gonangia differ somewhat from the dried specimens originally 

 described. They are top-shaped, 2 mm. long by 1 mm. in diameter at the widest part. 

 Distally they are strongly annulated, proximally they are almost smooth, while they 

 are terminated by a low dome, the tubular neck of the original specimen being 

 unrepresented. 



(ROY. SOC. EDIN. TRANS., VOL. XLV., 537.) 



