196 Mr. A. W. Waters on Australian Bryozoa. 



face smooth, with a spinous umbo below the aperture bearing 

 an avicularium (apparently semicircular) on the inner face ; 

 four spines above the oral aperture, in the central zooecia 

 also an erect avicularium with slit-like aperture. Oral aper- 

 ture (0*1 millim. wide) nearly round, contracted by two 

 lateral denticles near the lower part. Ovicell immersed, with 

 the front flat. 



The oral aperture in a case like this might be considered 

 either Schizoporellidan or Lepralian. The outer zooecia are 

 decumbent and the inner erect, resembling Rhynchopora 

 hisinnosa in this respect ; and in these two species the distal 

 edge of the oral aperture is crenulated, which is not usual in 

 the Bryozoa ; but I have also seen the same thing in the 

 growing cells of a Smittia. 



This differs from R. longirostris in the surface avicularia 

 being shorter and erect instead of decumbent ; there are no 

 perforations round the border of the zooecia, and the aperture 

 with its denticles is diffei-ent. 

 Loc. Living: Ball's Head, Port Jackson, 12 fath. 



60. Rliynclwpora ^Tofunda^ MacG. 

 (PI. VI. fig. 11, 16.) 



MhyncliojMra frofimda, MacGillivray, " Descriptions," &c, pt. iii., 

 Trans. Roy. Soc. Victoria, vol. xix. p. 192, pi. ii. fig. 8. 



In the specimens from Noumea there is a broad plate or 

 denticle directed inwards from the proximal edge of the aper- 

 ture, and the " unciform process " is very large and distinct. 

 These are the main characters on which it is separated from 

 R. hispinosa ; but, besides, the operculum enables it to be 

 distinguished, as the lower sinal curve is much broader and 

 the muscular impressions are at the side, whereas in R. hisjn- 

 nosa the muscles are attached to two bosses on the surface of 

 the operculum, as in 8. Cecilii &c. The upper border of the 

 operculum when seen from above appears to be nodulated j 

 but when seen laterally these nodulations are found to be 

 small teeth corresponding with the dentate border of the 

 aperture. This last structure also obtains in what I consider 

 R. hispinosa from Australia, but there the operculum is granu- 

 lated and has the muscular impressions in the usual position. 



This nodulated or dentate structure is found in many semi- 

 circular avicularian mandibles, and is known in two or three 

 opercula, but is not common. 



Loc. Port Phillip Heads ; Noumea, New Caledonia, 5 fath. 



