" ENDEAVOUR " SCIENTIFIC RESULTS. 182 



the cell ; border with a median anterior tooth and two on each 

 side, the first triangular, short and wide, the second still shal- 

 lower, often nearly obsolete, back excavated, adnate ; front of 

 the hydrotheca with an external longitudinal ridge terminating 

 in an elevated pointed crest over the anterior marginal tooth. 

 Two septal ridges in the internode, one opposite the hydrothe- 

 cal fold, the other at the base of the lateral sarcotheca?, some- 

 times a third between them. 



Mesial sarcotheca about three-fourths the length of the 

 hydrotheca, adnate most of its length, the free distal portion 

 usually directed more outward, terminal and inferior apertures 

 completely confluent. Lateral sareothecae divergent, adnate up 

 to the hydrotheca-margin, free terminal portion short, conical, 

 directed outward, terminal and inferior apertures continent, 

 Cauline sarcothecae stout, widely open above, two at the base of 

 each hydrocladium in front. 



Gonosome ? 



Colour. — Brown. 



This species, so far as the form of the hydrotheca is con- 

 cerned, somewhat resembles A. cariuata, Bale, which Billard 

 identifies with A. bracJiiata (Lamarck), but the habit is very 

 different, thepolypidom being usually unbranched. In one or two 

 instances new shoots were given off at right angles from the 

 bare denuded portions of old stems ; these however appeared to 

 be entirely new colonies, the hydrorhizal filaments by which they 

 were attached running round and along the supporting stem in 

 every direction. 



Other characters by which the species may be distinguished 

 from A. cariuata are — the larger size of the hydrotheca 

 ("48 mm. as against '32 mm. in length), the smaller and 

 shallower lateral teeth, and the general absence of the third 

 tooth on each side, which in A. cariuata is usually well marked, 

 and the different configuration of the apocauline side of the 

 hydrotheca, with the mesial sarcotheca. The last feature is 

 characteristic; in A. carinifera the free part of the sarcotheca 

 is rather abruptly bent outward, giving the sarcotheca, with the 

 hydrotheca, a "broken-backed" aspect, while in A. carinata 

 the sarcotheca has a uniform convex curve throughout, the free 

 portion being directed inward rather than outward. The 

 apertures of the sarcotheca^ are more widely canaliculate in 

 A. carinifera, and the laterals are directed more outward. 



The structure of the hydrocaulus is very different in the two 

 species. In A. cariuata the supplementary tubes which grows 

 up in contact with the primary tube are rather slender, and the 



