1867.] HARTT — ON CARBONIFEROUS LIMESTONES. 219 



Comparative Zoology, but I cannot satisfy myself that they are 

 specifically identical. There is a not uncommon Terebratula-like 

 shell, which shows, finely preserved, the characteristic loop of 

 Centronella (C. Anna Hartt). This is the first evidence we have 

 of the existence of this genus above the Devonian. 



Lamillibranchs. — Several species of Aviculopecten are 

 especially abundant. Of one of these, A. simplex Daws., Mr. 

 Meek writes me as follows : " There are among the Windsor 

 collection several good specimens of a little shell, exceedingly like 

 the so-called Pec fen pusillus (not a true Pecten), from the 

 European permian rocks. They are very similar, and, indeed, 

 almost the only differences observable on direct comparison with 

 good European specimens now before me. are the slightly more 

 ventricose form of the valves, and the rather more prominent 

 anterior ear of the left valve of the Windsor shell. Perhaps this 

 ear, in its left valve, is also a little more defined from the swell of 

 the umbo in some of the large specimens from Windsor, but on 

 comparing examples of the same size as the German specimens 

 here (which are not near so large as some figured in foreign 

 works), it is difficult to see characters by which they can be 

 distinguished. They are, in fact, more nearly alike than the figures 

 given of P. pusillus by different European authorities, or, in some 

 cases, by the same author, as varieties of that species. In short, 

 if found associated in the same rock at the same locality with P. 

 pasillus, few would suspect them to be distinct species." 

 Aviculopecten fallax McCoy ? Windsor and de Bert River, 

 Dr. Dawson ; A. Nova-Scotica Daws., Schubenacadie, Dr. 

 Dawson ; Pteronites Gayensis Daws., Gay's River, Dr. Dawson ; 

 Macrodon elegans De Koninck ? Windsor, Dr. Dawson and 

 Mr. Hartt; Modiola Pooli Daws., Windsor, Poole and Hartt. 

 Besides the above, there are several other Lamillibranchs not 

 yet determined. 



Gasteropods. — Naticopsis Howi, nob., one of the commonest 

 fossils of the Avon beds. I have detected only a single fragment 

 of Conularia in these beds, and this appears to be different from 

 the species of the overlying beds. 



Cephalopods. — A single Orthoceras has been collected at 

 Windsor. 



The Windsor limestone is well developed at Brookfield and 

 Stewiacke, and Gay's River, where it holds the same fossils as at 

 Windsor. I have not had an opportunity of examining extensive 



