BRYOZOA 



MacG., from Port Phillip Heads, has exactly similar zoœcia and ovicells ; and also the opercula 

 are just the same shape. MacGillivray says the young zoœcia of R. granulata hâve a fissure 

 in the ovicell, which is afterwards closed. The South African form is not in ail parts bila- 

 minate, but unilaminate parts coalesce, and thus become bilaminate. In the unilaminate 

 parts there are, on the dorsal surface, vibices and small avicularia, with semicircular mandibles, 

 as in the Australian R. granulata MacG. 



We are not now requiring proof, that for classification we must look principally to the 

 zoœcial characters, and that zoarial ones, when the) r are used, must be dealt with very 

 cautiously, though had such a striking case of identity of ail the minute characters, as in the 

 Australian reticulate R. granulata MacG. and in the bilaminate R. hilaminata Waters (just des- 

 cribed), been recognised and understood two générations ago, how much more advanced we 

 should now hâve been. 



A point, that has come before me in considering this species is mentioned for what 

 it is worth. So far as I am able to judge from my own collection, and from what I hâve seen, 

 there is no part of the world where there are so many massive and solid Bryozoa as South 

 Africa, and where gênera generally délicate, are found with thick calcareous growth, as examples 

 may be mentioned, Tennysonia stellata Busk ; large species of Heteropora, solid bilaminate 

 Steganoporella Bitskii Harmer ; bilaminate Schizoporella bimunita Hincks ; S. porelliformis mss., 

 a large bilaminate form ; large Adeona ; Mucronella conforta Busk ; Chaperia capense B. ; Meiu- 

 branipora elizabethiensis Waters allied to the small M . tubigera Busk ; Chaperia annulus var. 

 bilaminata Waters. In this respect the Antarctic forms are quite différent, as there are no 

 very massive species ; however Irom Patagonia there are some ; among others Aspidostoma 

 gigantea B. attains to a great size and is sometimes reticulate. 



The known Rcteporœ from S. America are R. magellensis Busk, and an allied species, 

 which I propose to call R. spatulifera, and also R. altisulcata Kirkpatrick, ail belonging to the 

 same group. This group is not apparently represented from the Antarctic. R. cellulosa L. has 

 been mentioned by Busk and Ridley from South America, but there is every probability, 

 that they were dealing with another species. Ridley refers to Busk's fig. 7, PI. CXXIII of 

 the British Muséum Catalogue, but Busk neither in the text, nor in the explanation of the 

 plates refers to fig. 7 so that we do not know what species it represents, but it may possibly 

 be R. magellensis Busk. 



The spécimen, which I propose to call R. spatulifera instead of forming a net work, is 

 composed of narrow strap-shaped branches, occasionally anastomosing at varying distances. 

 In the young zoœcia there is a broad spine at each side of the aperture, but in the older zoœcia 

 it is more délicate. Except in the zoarial form and in the spines this corresponds in ail 

 respects with R. magellensis Busk. 



Retcpora is not known from the Cretaceous, or any earlier formation, for though the 

 name has been used for some Paleozoic fossils thèse were in most cases FenestelliJœ. From the 

 l'>wer Tertiaries, the number of species mentioned is small, and some of thèse cannot be 

 again recognised, on account of the insufficient description and figures furnished. R. cellulosa 

 (L.-Smitt) has been given as from.lower Miocène or upper Eocene, but this is very doubtful, 

 whereas R. elegans Reuss, and R. rubeschi Reuss, from the lower Tertiaries, may be considered 

 good species. 



Some of Michelin's species are not Retepora but Hornera, and none could be recognised 



