THE HYDROIDS OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 81 



The gonangium, of which I have been able to find only one example, is borne on 

 the front of the stem immediately beneath a hydrotheca. It is oval in shape, tapering 

 below to form a distinct stalk, and truncated above by a wide aperture. This is 

 bounded by an insignificant thickened neck punctuated by small refringent chitinous 

 swellings on the inner surface. The walls of the gonangium are smooth. 



Measurements : — 





Internodes, length .... 



0-46-0-62 mm 



„ diameter near base 



0-03-0-04 „ 



Hydrotheca, length of contiguous portion 



0-10-0-14 „ 



,, ,, free portion * 



O-U-0-15 „ 



„ diameter at base . 



0-06-0-07 „ 



,, ,, ,, aperture 



0'04 mm. 



Gonangium, length .... 



0-74 „ 



,, maximum diameter 



0-41 „ 



One colony shows a pair of hydrothecse at an early stage of development, ere yet 

 the aperture, or the base, or the internal teeth had been formed. The stolon has so 

 regulated itself to the papillated surface of the Codiuon upon which it is growing that 

 the outline of its under surface is made up of a series of crescentic bays. 



The three- toothed margin, the three-flapped operculum, the prominent internal 

 teeth, the presence of a projection from the base into the interior of the hydrotheca, 

 together with the straight contours of the hydrothecse and the length of the internodes, 

 are points which distinguish this species. It has affinities with S. linealis, Warren, 

 1908. 



Locality. — Growing upon seaweed from Station 81, Abrohlos Bank, Brazil. Lat. 

 18° 24' S., long. 37° 58' W. Depth, 36 fathoms. Bottom deposit, coral. 20th 

 December 1902. 



Sertularia mayeri, Nutting, 1904. 



Small colonies, 5 mm. high — less than half the height of the type specimens — occur 

 creeping on Saragassum weed. Their characters agree with Nutting's description and 

 figures, and are identical with those of specimens collected by Mr Crossland at the 

 Cape Verde Islands (Ritchie, 1907,'^^ p. 505), although, owing to their smaller size and 

 the consequent restriction of the number of hydrotheca-pairs (in the largest specimen 

 mounted for microscopical examination there are only six pairs), the variation between 

 the proximal and distal pairs is not so marked as in the larger Cape Verde specimens. 

 Even here, however, the distinction between the distal long, narrow, closely forked, 

 gradually separating pairs, and the proximal short, dumpy, wide-spreading pairs is 

 sufficiently distinct and characteristic. It is indicated by the measurements below. 

 In the majority of the calycles two lateral teeth and a smaller median and superior 

 tooth, which succeeds an indentation in the wall of the hydrotheca and curves slightly 

 upwards, are very evident. 



* From the line of the stem to the tip of the lateral teeth. 

 TRANS. ROY. SOC. EDIN., VOL. XLVII. PART I. (NO. 4). 11 



