Aiistraliav,. Hydro ids. 14> 



Halk^oknakia akcuata (Laniouroux). (Plate X ITT., Figs. 1-4). 



Agldojihenia arcuata, Lamouroux, Hist. Polyp. Cor. Flex... 

 1816. p. 167, pi. iv., fig. 4a, Vj ; Kirchenpaner. Abh. 

 Nat. Ver. Hamb., v., 1872, p. 27, pi. i.. fig. 10. 

 Plumidarla arcuata, Lamai'ck, An. s. Vert. 2nd Ed. ii., 1836.. 



p. 166. 

 Aglaophtnia ar(iuat<i, Kiuuss, Coral, u. Zoopli. d. Siidsee^. 



1837, p. 24. 

 llalicornnvUi arcnata (in part), Billurd, Arch. d. Zool. 

 Exp.. 4 ser., vii., 1007, p. 366, fig. 13; Stechow, Zool.. 

 Jahrb., xxxii.. 1912, p. 369. 

 HaUcoriiaria cormtta, Allman, Journ. Ijin. Soc. Lond., 

 Zool., xix., 1886, p. 153, pi. xxiii., figs. 1-4. 

 Hydrocaiilus luonosiplionic, uid)i-anched or dividing dichoto- 

 mously one or more times; hydrocladia alternate, one on each' 

 internode, set at an angle of about 45 deg. to 50 deg., and slightly 

 directed forward ; nodes slightly oblique. 



Hydrothecae cup-shaped, deep and narrow, set at a wide- 

 angle (about 75 deg. to 80 deg.), no true intrathecal ridge, 

 but the apocauline wall somewhat incurved at the point where- 

 it is interrupted by the hydropore, wdiich is large and distinct; 

 aperture with a strong median anterior incurved tooth and 

 usually with three teeth on each side, of wliich the first and 

 third are large and everted, while the middle one is small and 

 incurved, the latter often more or less obsolescent or totally want- 

 ing; back produced upward into a long erect lobe with the edges 

 curved towards each other on the outer side, hydropore Avith one or 

 two minute denticles above and below. No septal ridges in th& 

 internode. 



Mesial sarcotheca quite erect in the proximal portion, distal half 

 directed forward, either parallel with the hydrocladium or more- 

 obliquely; free part compressed laterally, very stout at the part 

 just above the hydrotheca, where the strongly salient aperture is 

 situated, terminal portion tapering very rapidly to the acute closed' 

 point. Lateral sarcothecae adnate, saccate, with two small circular 

 apertures close to the free margin, the lower onebecoming. in those- 

 near the end of the hydrocladium. produced into a large tubular- 

 mouth, or even into a long closed pointed horn, having its own- 

 lateral aperture, while the tipper circular orifice becomes obsolete. 

 Cauline sarcothecae similar to the latoi-als, two, close together, at 

 the base of each hvdrocladiuiii in front, and one at tlie back of each: 



