38 THE VOYAGE OF H.M.S. CHALLENGER. 



Aglaophenia attenuata is a small and delicate species. The anterior bifid toutli of 

 the hydrotheca and the open corluda afford good diagnostic characters. The spur- 

 like nematophores at the base of the costae are well developed. 



A comparison of the open corbula of Aglaophenia attenuata with the proper Lytocarpal 

 phylactoearp, as, for example, that of Lytocarpus myriophylhim, or of Lytocarpiis racemi- 

 ferus, and AcantJwcJadium hiixleyi of the present Eeport will show that the mere fact of 

 the costfe not being adnate by their edges affords no sufficient ground for generic 

 separation from Aglaophenia, more especially as in one species at least {Aglaophenia 

 JiUcida, see p. 36) closed and open corbulae are borne by the same colony ; in Aglaophenia, 

 however, the cost?© of the corbula, whether open or closed, are always more or less in the 

 form of flat serrated leaflets, "udthout hydi'othecje or other appendages ; while in such 

 open forms of phylactoearp as occur in the genera Lytocaipns and Aeanthocladiinn the 

 costte are either long, curved, rod-like or sabre-shaped appendages, each canying a 

 hydrotheca, or are in the form of a series of strong spines without hydrothecje, or are 

 simply replaced by a series of large nematophores. 



Dredged in Simon's Bay, Cape of Good Hope ; depth, 10-20 fathoms. 



Aglaophenia aeacia, n. sp. (PI. XII. figs. 1-4). 



Trophosome. — Colony attaining a height of about six inches ; stem monosiphonic, 

 pinnately branched, branches opposite or sub-opposite, rather distant, carrying the hydro- 

 cladia, which are about two-tenths of an inch in length, and are also borne by the main 

 stem in the intervals of the branches. Hydrothecse deep, with deeply serrated margin, 

 intrathecal ridge very short, situated just above the fundus of the hycbotheca ; mesial 

 nematophore adnate to the wall of the hydrotheca for about one-half their height, and 

 then terminating as a free short spine which does not reach the level of the hydrotheca 

 margin ; lateral nematophores stout, slightly overtopping the margin. 



Gonosome.— Gov\m\sd rather short and deep, with about six paii's of closely adnate 



COStiB. 



The hal)it of Aglaophenia acacia is somewhat loose and spreading. The main stems 

 continue unbranched for four or five inches from the root, and then give off opposite or 

 nearly opposite branches, which confer on the species a very distinctive aspect. The dis- 

 position of the primary branches is truly pinnate, while these again carry the pinnately 

 disposed hydi'ocladia. The ramification is thus properly bipinnate, though the distances 

 between the primary branches and between the hydi'othecal ramuli give to it an aspect 

 very different from that of Aglaophenia macgillivrayi, and of other bipinnate Plumu- 

 laridce with their closely approximated branches and hydrocladia. 



Aglaophenia acacia is a deep-water species, having been dredged along with 

 Aglaophenia Jilicida, at Station 75, July 2, 1873, lat. 38° 37' N., long. 28° 30' W. ; 

 depth, 450 fathoms; liottom, sandy. 



