TIYMKOITIS UnidGS. 29 



liollow clianiber, wliicli terminates in an elevated pointed crest over the 

 anterior marginal tootli ; and (5) the stiiioture ol" the corbula, and the 

 arrangement of the sarcothecae on the leaflets. 



Re»i(irJ,s. — Whitelegge^ in his list of Hydroids from Lord Howe 

 Island, includes " Halicornaria, sp. nov. ? ", and specimens so labelled in 

 the Australian Museum collection prove on examination to be identical 

 with AiihtnpJieuiK hoire)i.^is. There is also preserved in the Macleay 

 Museum a specimen of this species from an unknown locality, collected 

 bv the '' ('hevert " expedition. The itinei^ary of this expedition did not 

 include Loi-d Howe Island, the '' ('lievert's " movements being confined to 

 the Austiulian coast (the inner passage from Percy Island to Cape York), 

 New Guinea, and Toi^res Straits. 



j^or. — Middle Beach, Lord Howe Island, South Pacific Ocean. This 

 specimen has been selected as the holotype. 



Jlolnfiipe. — In the Australian Museum, Sydney. 



Genus AciLAOPiiRXOPSis, Fewl-es. 



Aghu'lJtPiwp^l.-<, Fewkes, Bull. Mus. Comp. Zool., viii., 1881, p. 132. TJ., 

 Nutting, .Vmerican Hydroids, pt. I., — Plumularidse, 1900, p. 118. 

 The genus Aghiopleuopsis, with ]iii:-<iifa for its type, was described by 

 Fewkes in 1881 from specimens taken by the " Blake " Expedition. In 

 1900 Nutting added two new species, .1. (0 distau!<, and A. vernlli, and 

 also referred to this genus Cltidocarpny corimtus, Verrill. The genus has 

 hitherto been known only fi^om North American waters. The occurrence 

 in Australian seas of a fifth species is, therefore, particularly noteworthy. 

 The bathymetrical distribution of the American species ranges from 200 

 to 1,497 fathoms. The Austi^alian representative was dredged in 50 

 fathoms. 



A(;LA0PHR\01>SI^^ VACA, sp. 710V. 



(PI. v., fig. 3-7 ; PI. vi., fig. 2.) 



Trophosome. — Hydrocaulus polysiphonic, branched, reaching a height 

 of 16 cm. The hydrocladiate tube is divided into regular internodes by 

 distinct nodes. Each internode bears a single hydrocladium. The 

 hydrocladia are slender, alternate, both series springing from the front of 

 the hydrocladiate tube and directed forwards ; nodes slightly oblique. The 

 hydrocladia are divided into a series of regular internodes, each of which 

 bears a solitary hydrotheca. 



The hydrothecae are deep, oval in shape, narrowing towards the base, 

 the axis of the hydrotheca lying almost parallel with the hydrocladium. 

 There is a well-developed intrathecal ridge near the base, projecting from 

 the adcauline wall, and reaching a little more than one-third across the 

 cavity of the hydrotheca. The aperture of the hydrotheca is circular, 

 and has a well-developed anterior tooth ; the border is otherwise entire, 

 smooth, or very faintly undulated. The back is adnate. The hydrothecal 

 iutei^node is provided with three septal ridges, one opposite the 

 intrathecal ridge, another behind the lateral sarcothecae, and a third near 

 the base of the internode. Besides these a small septum generally runs 

 across the cavity of the mesial sarcotheca. 



■» Whitelegge in Etheridge— Mem. Anstr. Mus., ii., 1889, p. 41. 



