DESCRIPTIONS OF TWO NEW HYDROIDS, AND A REVISION 

 OF THE HYDRO ID-FAUNA OF LORD HOWE ISLAND 



KV 



Iv A. Bi;ii;i;s, B.Sc, Zoologist, Austi*alian Musenm. 



(Plates v.-vi.) 



I. — DEScrari'ioxs ok thk Nkw Species. 



Family PLUMULARID^. 



Oemis Aglaophenia, Lamouroux. 



Aglaophexia howensis, sp. nov. 



(PI. v., fig. 1-2; PI. vi., fig. 1.) 



TrophoscmiP. — Hydrocaulus monosiphonic, nii branched, simply pinnate, 

 attaining a height of G cm. Tlie stem is diA'ided into regular iuternodes, 

 sepai'ated by oblique nodes, which slope successively in opposite 

 directions. Each iutei-node bears a single hydrocladium. The hydi^o- 

 cladia are slender, alternate, close, both series nearly in one plane, and 

 rising at an angle of about 35°-40° ; nodes slightly oblique. The hydro- 

 cladia are divided into a series of regular internodes, each of which bears 

 a solitary hydro theca. 



The hydrothecee are borne nearly on the front of the hydrocladia. 

 They are closely set, sub-cylindrical, with the axis of the hydrotheca 

 lying away from the hydroclade at aii angle of about 40°. There is a 

 well-developed anterior intrathecal ridge proceeding from about the 

 middle of the front of the cell and extending to aboTit its centime, where it 

 ends in a hammer-like thickening. There is in addition a small pro- 

 jection in front of the hydropore with a rounded median tooth, which is 

 cleai'ly a rudimentary posterior lidge. The hydropore is parallel with 

 the hydrocladium, or nearly so, but raised above it. The border of the 

 hydrotheca has a well-developed median anterior tooth, which is incurved, 

 and four teeth on each side. The first pair of lateral teeth from the 

 front are triangular, rounded at the apex, and strongly everted ; the 

 second pair, roughly rectangular in appearance, ai'e bent inwards ; the 

 third pair are broad, rounded at the apex, and strongly everted ; tlie 

 fourth pair are narrow, pointed, and lie behind the lateral sarcothecae. 

 The back is adnate. The front of the hydrotheca is provided with an 

 external longitudinal hollow chamber extending from the anterior 

 intrathecal x'idge, and tenuinating in an elevated pointed crest over the 

 anterior mai'giual tooth. Hydi^othecal internode without septal ridges. 



The mesial sarcotheca is about half the length of the hydrotheca, 

 and is adnate for about half its length, tlie free distal portion usually 

 being directed more outward. The terminal and inferior apertures are 

 completely confluent. A small septum runs across the cavity of the 

 mesial sarcotheca. The lateral .sarcothecee are small, adnate up to the 

 margin of the hydrotheca, and project slightly beyond it ; the terminal 

 and inferior apertures are confluent. There are three cauline sai'cothecee ; 

 two on the anterior surface of the rachis at the base of each hydro- 

 cladium, the distal anterior sarcotheca being similar to tlie laterals, but 

 larger, or with two orifices bordering the free margin ; while the 

 proximal antei-ior sai'cotheca is smaller, and almost oval in outline, with 

 a solitary wide superior aperture. The thiid cauline sai'cotheca is 

 similar to the laterals in shape, but larger, and is situated at the back of 

 each axil. 



