31 S PROVISIONAL SPECIES. 



Development of Gonosome. — September. 

 Habitat. — In tide pools near low-water mark. 

 Bathymetrical distribution — Laminarian zoue. 

 Locality. — Torquay, G. J. A. 



The small size of the present species, its more simple ramification, and the fact that its 

 stems consist of a single tube instead of being fascicled or composed of numerous tubes coalesced 

 into a dense bundle, at once distinguish it from the other British species, while these features 

 present a combination of characters which also prevent its being confounded with any non- 

 British forms hitherto described. 



Hincks ('Brit. Hydr. Zooph.,' p. 112) speaks of a form intermediate between Boiic/ainvillia 

 musciis and B. ramosa, having fascicled stems like the latter, but in other respects more closely 

 resembling B. muscus. It is probably a variety of B. ramosa. 



The medusa, on liberation, diflPers in no respect from that of BougainvUtia ramosa at the 

 same period. We have as yet no evidence regarding its adult form, which probably resembles 

 that of Bouyainvillia ramosa. 



PROVISIONAL SPECIES. 

 " BouGAiNviLLiA Mertensii," Alex. Agassiz. 



Under the name of " Bovgainvillia Mertensii" Mr. Alexander Agassiz describes, but 

 without any figure, a trophosome which, he informs us, " grows cpiite luxuriantly, attaining 

 a height of nearly two and a half inches ; the stems are very stout, particularly in the main 

 branch, which, near the base, is exceedingly robust ; the branches are, at least, three times as 

 stout as those of the hydrarium (trophosome) of Bougainvillia superciliaris, which is slender 

 and always branches quite loosely."^ 



The trophosome thus described is referred by its discoverer to a medusa which he regards 

 as identical with that obtained by Mertens in Behring's Straits, and described by Brandt under 

 the name of Hipimcrene BougainviUii, but for which Professor Agassiz proposes the name of 

 " Bougainvillia 3'Iertensii."~ 



As, however, the medusa has not been traced to the trophosome, there is no direct proof of 

 the relation between the two, and the species cannot, therefore, be yet regarded as established. 



The medusa appears to belong to the form with rounded manubrium and very nuich 

 branched labial tentacles. Both it and the trophosome were obtained upon the western coast of 

 Mexico, and they are thus Pacific representatives of the Bougainvillia form as seen in other species 

 on the east and west shores of the Atlantic. 



* Alex. Agassiz, ' Illust. Catal.,' p. 152. 



- Louis Agassiz, ' Cont. Nat. Hist. U.S.,' vol. iv, p. 314. 



