16 ME. A. W. WATERS ON THE MARINE 



species which I have long known in manuscript), there being important 

 specific differences in each. 



The closures and tubules are very important, as the same thing occurs in 

 various recent and fossil Cheilostomata *, though often called " opercula," 

 as it has frequently been supposed that the aperture was closed by this 

 calcareous film, independently of the chitinous operculum, whereas from 

 analogy we may feel sure that the calcareous deposit was formed over the 

 operculum, there being therefore an important structural difference in the 

 closures of the Cheilostomata and Cyclostomata, so that, in fact, it is doubtful 

 whether the name closure should be used for the deposit in the Cheilostomata. 



In Meliceritites (fossils very abundant in the Jurassic and Cretaceous 

 formations) the closures with tubules are very common, and I have shown 

 that the family had avicularia with mandibles; it also had opercula, and we now 

 know that such closures and tubules are not restricted to the Cyclostomata. 

 The new layer in some species of Meliceritites has the distal wall passing 

 over the operculum of the under layer just as described in Schizoporella 

 nivea t, Busk. Further, the shape of the zooecia in Meliceritites is not regu- 

 larly tubular as in Cyclostomata. As we have several truly Cheilostomatous 

 characters 1 have protested against Meliceritites being called Cyclostomata ; 

 on the other hand, Gregory and Levinsen have shown that the large ovicells 

 have Cyclostomatous characters, which may be sufficient to prevent the 

 family being placed with Cheilostomata ; certainly it should never be called 

 Cyclostomata. 



Levinsen \ speaks of layers of growth being a Cyclostomatous character, 

 but there are several Schizoporella' with multi-layered growth, and this is 

 often the case in Adeonella, Cellepora, Micropora, &c. 



In examining the opercula of S. unicornis in decalcified material I came 

 across a very abnormal double one, having two proximal ends, each with a 

 wide arc, like those of the normal form, and there are four muscular dots 

 (fig. 22). 



Loc. Generally distributed in the northern hemisphere and the tropics. 

 St. Vincent Harbour, Cape Verde Islands, 10 fath., collected by Crossland. 



Schizoporella spongites (Pallas), Smitt. (Plate 2. figs. 10-13.) 



Eschara spongites, Pallas (pars), Elenclms Zoophytorum, p. 47 (1766). 



Hippothoa spongites, Smitt, Floridan Bryozoa, p. 42, pi. 8. figs. 161-163 (1873). 



Schizoporella spongites, Thornely, Report on Pearl Oyster Fisheries of the Gulf of 

 Manaar, p. 114 (1905); Levinsen, Morph. & Syst. Studies on the Cheil. Bryozoa, p. 324, 

 pi. 18. figs. 4«-ri (1909) ; Osburn, "The Bryozoa of the Tortugas Islands, Florida," Publ. 

 182, Carnegie Inst., p. 207 (1914). 



* "Bry. from Zanzibar," Proc. Zool. Soc. 1913. p. 504. • 



t " Bry. from Zanzibar," Proc. Zool. Soc. 1913, pp. 503, 504. 



t " Studies of the Cyclostomata Operculata," K. Danske Vid. Skr. vol. x. (1912) p. 19. 



