NO. 3 fraser: hydroids 141 



tubes, with no very definite arrangement of the nematophores, although 

 there is usually a nematophore near the base of each hydrotheca. On 

 the distal portion of the stem and branches, there are still two rows of 

 hydrothecae but they are not so nearly in the same plane; the peripheral 

 tubes are much reduced in number. The nematophores show up veiy 

 well here, at the base of the hydrothecae. The hydrothecae are small, 

 nearly tubular but the tube is regularly curved so that the margin is 

 parallel to the stem or branch, adnate for approximately half the length. 

 Gonosome. — Not observed. 



Sertularella clausa (Allman) 

 Plate 20, Fig. 10 



Sertularia clausa Allman, Challenger Hyd., Part II, 1888, p. 54. 

 Sertularella clausa Nutting, Am. Hyd., Part II, 1904, p. 93. 



Trophosome. — Colony reaching a maximum height of 23 mm., 

 slightly and irregularly branched; branches like a portion of the main 

 stem, but they come off abruptly with a pronounced constriction at the 

 origin. Sometimes the basal internode of the branch is slightly wavy in 

 outline. The nodes are oblique and the internodes turn to the right and 

 to the left alternately, making the branch slightly zigzag. One hydro- 

 theca is given off from each internode, near its distal end. The hydro- 

 theca is slightly curved, nearly tubular, but slightly tumid in the lower 

 portion, approximately one-half free, surface smooth. Margin with four 

 low teeth; operculum with four well-defined flaps. 



Gonosome. — (Not previously described.) Gonangium arises from 

 the main stem or branch, with constricted base similar to that of the 

 branch, and a very short, tapering pedicel; ovate, with a distinct neck 

 and four low, blunt, irregular teeth on the margin; sometimes there is 

 a tendency to corrugation in the distal third, the corrugations being low 

 and rounded. 



Sertularella erecta, new species 

 Plate 21, Fig. 11 



Trophosome. — Stem simple, usually unbranched, rather rigid, aris- 

 ing from a stolon to a height of 20 mm. Nodes scarce and irregularly 

 placed, or absent. Hydrothecae appear in very regular alternation on the 

 two sides of the stem, nearly one half of the adcauline side is adnate. 

 The basal portion is slightly turgid, the distal portion is turned out- 

 ward, nearly at right angles; the adcauline side of this portion is con- 



