SYDNEY J. HICKSON AND F. H. GRAVELY. 



x 



FAMILY PLUMULARIIDAE. 



PUIMULARIA GLACIALIS. 



(Plate III., figs. 23, 24.) 



Locality. "East end of Barrier," January 29th, 1902; 100 fms. 



From the nature of the hydrorhiza, which was curved, it seems probable that 

 the specimens of this species were attached to a weed or zoophyte. 



Hydrosome. A stout fascicled hydrocaulus (fig. 23) 300 mm. in height and 

 2*5 mm. in diameter near the base arises from the densely matted but imperfectly 

 preserved hydrorhiza. 



In the constitution of the hydrocaulus there is a single tube (fig. 23, t. lid.} 

 giving off, alternately right and left, hydrocladia which may be 30 mm. in length 

 and are usually divided into two equal branches. Supporting this single tube that 

 bears hydrocladia are several other tubes (t. sp.) which bear nematophores only. The 

 supporting tubes do not surround the hydrocladia-bearing tube, but leave it exposed 

 on one side. The hydrocladia-bearing tube is divided into a series of intcrnodes 

 1 mm. in length, and it becomes free from its supporting tubes at the distal end, so 

 that the hydrocaulus then becomes monosiphonic. In Plumularia profunda (Nutting, 

 18 : pp. 66-67; PI. VIII., figs. 2-3), to which our species has some affinities, the 

 supporting tubes entirely surround the hydrocladia-bearing tubes, and the iuternodes 

 are of two kinds, longer ones supporting two hydrocladia and shorter ones bearing 

 only one hydrocladium. Moreover, in Plumularia, profunda the hydrocladia are 

 supported on processes arising from the proximal end and not from the middle of 

 the internodes as they are in our species. 



A short hydrotheca (0'2-0'3 mm. in height), adnate to the hydrocaulus but 

 not adnate to the hydrocladium, is found at the base of each hydrocladium (fig. 23). 

 The other hydrothecae are cup-shaped, 3 mm. in length and 2 mm. in diameter 

 at the mouth. One, or sometimes two, arise from each internode of the hydrocladia, 

 and each one is guarded by two nematophores above (i.e. distally) and a single one 

 below. The margins of the hydrothecae are entire. 



Although the label of the bottle containing these specimens bears the inscription 

 "has been dry," some of the hydranths are sufficiently well preserved to enable us 

 to make out some features of the structure of the soft parts. The rounded hypostome 

 is surrounded by a single circlet of about fifteen tentacles, each about 0*15 mm. 

 in length. 



Gonosome. The female gonothecse are 1 ' x ' 5 mm. in size, and have a 

 remarkable shape (fig. 23, ? yth.). The aperture is found on the distal flattened 

 end of the pear-shaped structure, but instead of being at right angles to the stem, 

 is turned inwards through an angle of 45 so as to face inwards and upwards. This 



