SCIENTIFIC KKSUI.TS. 184 



adnate, saccate, with one or two tabular apertures, one directed 

 downwards at right angles with the hydrotheca, the other, when 

 present, directed upwards and forwards, but often merged com- 

 pletely in the wide lateral aperture. Cauline sarcotheca^ similar 

 to the laterals but with more apertures, two on the rachis at the 

 base of each hydrocladium, and a third at the back of each 

 axil. 



Gronothecre about three times the length of the hydrotheca 3 , 

 campatmlate, truncate. 



Colour. Brown, stems very dark. 



Among the Hydroids described in the first part of this 

 Report were some small specimens of Halicornaria, found over- 

 running the stems of large Aglaophenice, and which, while 

 differing slightly from Billard's account of H. urceolifera, 

 seemed sufficiently close to that description to admit of their 

 being referred to the species. Later on other specimens were 

 obtained, which correspond pretty closely with Lamarck's type, 

 and I consequently distinguished the first form as var. scatidens. 

 It differs from the type principally in its smaller si/e about 

 four to five inches and in the mesial sarcotheca, which has 

 nearly always a single terminal aperture instead of two. 



The present form is represented by a small number of shoots 

 about a foot in height, or slightly more than Lamarck's speci- 

 men, and which all spring from the hydrorhiza in a cluster, 

 thus not sharing in the parasitic or climbing habit of the smaller 

 variety. Some are unbranched, but one or two have a small 

 branch near the summit. Most of the stem-iuternodes which I 

 examined bore two hydrocladia, those bearing a single one being 

 rare. Some specimens of var. scandens, with thick stems, agree 

 in this particular; in others, where the stems are more slender, 

 the shorter internodes preponderated. The large specimens are 

 darker in colour, especially the stems, which are nearly black, as 

 described by Lamarck. 



The minute structure is very similar to that of var. scandens, 

 the most conspicuous differe^e being in the mesial sarcotheca?, 

 which have two small sub-tubular terminal orifices placed side by 

 side, and distinct from the wide inferior opening. Another 

 distinction is that in the type form the first pair of lateral teeth 

 of the hydrotheca-border are considerably shorter than those of 

 var. xi-ni/ili'nx, while an inward bulging of the front of the 

 hydrotheca, under the mesial sarcotheca, is more apparent. 

 The back lateral lobes of the border scai-cely rise beyond the 

 lateral sarcotheca?, and are therefore still more inconspicuous 

 than in the small variety ; in both forms however, this lobe is 

 feebly developed and apt to be obsolete. 



