HYDKOIDA, — RAT/E. 31 



me in the singular irregularity of the lateral lobes, which is very 

 pronounced in most of them. The sarcothecae are exceedingly 

 thin and transparent, yet endure treatment with boiling liquor 

 potassa? without injury. Their gi-eatest diameter is about the 

 middle rather than at the extremity. Those which are most often 

 wanting are the pair below the axils, each of which springs from 

 a rounded thin area, which, in the newer parts of the branches, 

 looks like a perforation. The two sets of hydrocladia are in the 

 same plane, and the first of the supplementary tubes which form 

 the polysiphonic stem commonly runs up the front of the primary 

 tube. 



The ramification, as displayed in the small pinnately-arranged 

 branchlets, is very singular. Each one is supported by Ihe 

 primary tube immediately above a hydrocladium. Its cavity 

 however is not directly continuous with that of the parent branch, 

 with which it communicates only indirectly, by a narrow passage 

 leading into the apophysis of the hydrocladium immediately below 

 it. On its distal side the base of the new branch gives origin to 

 a supplementary tube running up the parent branch, and 

 between this tube and the cavity of the new branch the 

 communication is uninterrupted. 



The only closely related form which I know of is P. hertwigi, 

 Stechow, from Japan. In that species the hydrothecse have 

 nearly the same general form as those of P. asymmetrica, 

 but the lateral lobes are equal, while there is no intrathecal ridge. 

 A more remote affinity exists between P. asymmetrica and P. dlata, 

 Bale, which two species however exhibit the two extremes of size 

 among the Plumulario?. 



Loc. — Great Australian Bight, 40 to 100 fathoms. 



Genus Aglaophenia, Lamourou®. 



Aolaophenia crucialis, Lamourou.v. 



Aglaophenia crucialis, Lamouroux, Hist. Polvp. Coral Flex 

 1816, p. 169. 



Plumnlaria crucialis, Blainville, Man. d'Act., 1834, p. 478. 



Anisocalyx crucialis, Costa, Fauna del regno di Napoli Zoofiti 

 Napoli, 1838, p. 19. 



Aglaophenia crucialis, Billard, Comp. Rend. Acad. Sci., cxlviii 

 1909, p. 1063; An. Sci. Nat,, Zool. (9), ix., 1909, p. 33l' 

 Ritchie, Mem. Austr. Mas , iv., 16, 1911, p. 864, pi. lxxxvi 

 figl. 



