BEYOZOA FE03I ATJSTEALIA. 



429 



but as I have come across many intermediate stages, and find all 

 the characters of G. alata present, I think it must be looked upon 

 as identical, though, perhaps, coming from a different part of the 

 colony. 



In the recent C. ventricosa the spinous process is very variable in 

 the same colony, sometimes being very large and sometimes entirely 

 wanting ; and this is also the case in G. taurina. 



The aperture is 0-07-0-08 mm. wide. 



Loc. Living: Bass's Straits (Harv.), Port Fairy (Dawson), 

 Queenscliff (MacGillivray) , Tasmania (W.). Fossil: " S.W. Vic- 

 toria," Mt. Gainbier, Muddy Creek, Bird Rock, Waurn Ponds. 



3. Catexicella ampla, Waters. 



Catenicella ampla, Waters, Foss. ChiL Bry. from S.W. Victoria, 

 p. 317, pi. xvi. figs. 46, 50, and Chil. Bry. from Mt. Gambier, 

 p. 259. 



This speeies may be taken as the type of a group of Catenicella, 

 which at first sight appears . to vary a good deal from the type de- 

 scribed when we spoke of O. alata, p. 428; but when calcined 

 and decalcified specimens of recent forms are examined, we then 

 find that, although the relative proportions of the different parts 

 vary, yet all the same structures are present. Among recent forms 

 Catenicella ponder osa, Goldstein, will perhaps furnish the best ex- 

 ample ; for upon examining decalcified preparations, the supraavicu- 

 larian compartment, although very small, can easily be distinguished ; 

 on the other hand, the avicularian chamber, instead of being tubular, 

 is very large. 



Fig. 3. 



Letters as fig. 2. pi, protecting plate. 



In this group we find a structure which has not yet been de- 

 scribed ; that is, a calcareous oval plate on the front of the zooecium, 

 and which can be seen through the fenestras, extending half across 

 them. This structure will be made clear by a reference to the dia- 

 gram, fig. 3, and to fig. 6, PL XII., of the recent C.ponderosa, Goldst., 



