268 ME. AETHUR W. WATEES ON 



lidce, according to some, only includes forms whieli have two 

 zooecia in a row, the branches being united by barren dissepiments ; 

 others would also place in the family those which have several rows 

 of zooecia. At any rate, our Naples specimen in these respects 

 resembles typical Mnestella, but when other characters are 

 examined we see that the striking resemblance is merely zoarial. 

 The dissepimeuts are tubular, which, so far as I can make out 

 from published figures and from specimens in my collection, is 

 never the case in Fenestella ; as to the value of this point we are 

 scarcely in a position to form an opinion, whereas the differences 

 in the shape of tlie zooecium are of more importance. 



In 1878 I pointed out that in one species of Fenestella there 

 are two denticles in each cell *, and TTlrich, in his ' Palaeontology 

 of Illinois,' has shown that these denticles are largely found in 

 the Cryptostoraata, a suborder proposed by Vine; and to repeat 

 what I have elsewhere said f, tliese denticles are usually at the 

 base of what Vine | and Uli'ich § call a " vestibule," — that is to 

 say, there is within the shell a tubular shaft up to the external 

 opening, so that it is at right angles to the "primary chamber," 

 which, might be called the zooecial chamber. 



There are several recent Chilostomata which have zooecia the 

 shape described as occurring in Palaeozoic Cryptostomata, among 

 others CJiildonia Cordierii may be mentioned, and there are 

 some which have a hemisepta at the point of attachment of the 

 operculum ; so that there seems very strong reason for following 

 TJlrich in considering that the Cryptostomata, including Je^zes^eWa, 

 show closer relationship to living Chilostomata than to Cyclo- 

 stomata. Now when we compare the shape of the zooecia of 

 P. parallelata, we find none of the characters of Cryptostomata 

 and there are no hemisepta. 



There is no affinity between Betepora and Fenestella, although 

 with regard to zoarial characters both may be fenestrate with 

 dissepiments, or reticulate through the branches anastomosing, 

 while a few are simply branched. 



The Eetepora deserta, Waters, which I described || fossil from 

 Bairnsdale, has somewhat the same structure as Falmicellaria 

 parallelaia. 



* " Remarks on some Fenestellidse," Manchester Geol. Soc. vol. xiy. 1878. 

 t Ann. & Mag. Nat. Hist. ser. 6, vol. viii. p. 50. 



I Quart. Journ, G-eol. Soc. vol. xl. p. 332. 



§ " Palseozoic Bryozoa," Palaeontology of Illinois, vol. viii. 1890. 



II Quart. Journ. Geol. Soc. vol. xxxviii. p. 511. 



