HYDROIDA. HALE. 49 



idea rather of a group of five or six stems with their bases all 

 bound together in a fascicle by hydrorhiza-like filaments. The 

 present specimen resembles a single one of these stems, and it has 

 one or two filaments adhering an inch or so above the point at 

 which it has been broken off, A characteristic feature is the 

 condition of the anterior tooth of the hydrotheca, which is 

 everted and stands immediately opposite the lateral orifice of the 

 anterior sarcotheca, just as in Kirchenpauer's species. On the 

 other hand the form of the hydrotheca in Kirclieupauer's 

 figure is very different, being much shorter. Dr. Hartlaub 

 obligingly undertook to examine Kirchenpauer's type, but the 

 specimen turned out to be merely A. divaricata. That species 

 certainly has the hydrothecas more like the figure in their general 

 form, but they do not have the anterior tooth everted ordinarily, 

 and the habit-figure does not resemble A. divaricata. The figure 

 of the hydrotheca is bad, whether intended for A. divaricata or 

 the present species, and under the circumstances it is impossible 

 to say whether Kirchenpauer has described an aberrant form of 

 A. divaricata, or whether an error has been made in labelling 

 the type specimen. 



The whole polypidom is lax and slender, the compound stem 

 consisting of few tubes. As in A. divaricata the branches 

 spring from the accessory tubes, and commence with a series of 

 about ten internodes bearing sarcothecaa only. The internodes 

 of the hydrocladia are unustially slender. In some parts of the 

 colony the anterior teeth of the liydrothecas were without the 

 characteristic outward bend, but as this bend is found in the 

 portions where the perisarc is most perfectly preserved, I 

 conclude that it is the typical form. 



Loc. Bass' Strait. 



GENUS HALICORXARIA, Busk. 



HALICORNARIA BIROSTRATA, sp. nov. 



(Plate iv., fig. 5 ; Plate vii., fig. 6.) 



Hydrocaulus monosiphonic ,(unbranched ?) about five inches 

 in height ; hydrocladia alternate, one on an internode, at an 

 angle of about 45, and both series directed towai'ds the front ; 

 nodes transverse or scarcely oblique. 



Hydrothecte long, tubular, proximal part parallel with the 

 internode, distal part recurved upward, a narrow anterior 

 intrathecal ridge immediately below the aperture ; border entire 

 in front and behind, a large angular lobe at each side aboiit the 



