THE HYDROIDS OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 77 



No gonangia were present. 



Locality.— Station 313. Lat. 62° 10' S., long. 41° 20' W. Depth, 1775 fathoms. 

 Bottom deposit, blue mud and boulders. 18th March 1903. 



The distribution of the species is almost world-wide, but it has not hitherto been 

 recorded from Antarctic Seas. 



Sertularella fusiformis (?) Hincks, 1861. 



A few minute simple stems, 7 mm. high, rising from a stolon creeping upon a sea- 

 weed. The slightly geniculate stems are divided into internodes which vary consider- 

 ably in length, those nearer the base being longer than the more distal, the former 1*08 

 mm. as against an average of 0'61 mm. for the latter. The internodes are narrow, only 



Fig. 3. — Sertularella fusiformis (?) Portion of stem, x 40. 



0"06 mm. in diameter at the base, but they widen upwards until a ledge is formed upon 

 which the base of the hydrotheca rests. They are separated by slanting nodes, immedi- 

 ately above which occur one or two rings, while the remainder of the internode is more 

 or less definitely wrinkled. 



The hydrothecae lie in the same plane, are alternate, and are placed one on the distal 

 end of each internode. Rather more than half of each is free, the free portion leaning 

 well away from the stem. In shape they are flask-like, bulging proximally, while towards 

 the distal end there is formed by a sudden constriction a distinct " neck," which is sur- 

 mounted by the four-toothed margin. The walls of the hydrothecse are smooth 

 externally, but just within the margin the inner surface bears four distinct blunt teeth 

 which lie midway between the marginal teeth. 



