148 
Nucula tumida, Ten. Wds., is not acknowledged as a recent 
species. 
Placunanomia Ione, Gray. Messrs. Hall and Pritchard claim 
this as an Eocene species on our authority, and quote it as being 
so noted on page 20 of Dennant’s “ Notes on the Muddy Creek 
Beds.” They are mistaken. It is there marked Y, which 
indicates the upper beds. 
TE. 
We desire to acknowledge the scientific candor with which 
Messrs. Hall and Pritchard have withdrawn some of their con- 
clusions concerning the classification of the Eocenes in deference 
to the arguments advanced by us. 
These authors, however, take exception to our figures regarding 
the number of species at Muddy Creek and Spring Creek respec- 
tively which pass up into the Miocene, and give others which, as 
they say, differ widely from those quoted. In reference to this 
matter we remark (1) that rare forms, or those concerning which 
there was likely to be a difference of opinion, were intentionally 
omitted ; and (2) that the figures furnished by Messrs. Hall and 
Pritchard for Muddy Creek are apparently mainly derived from 
the 1888 list, which now needs considerable revision. In this 
connection we may also observe that a few minor errors appear in 
the distribution assigned to certain Muddy Creek species described 
in the Society’s Transactions, which are hereby corrected as 
follows :—Zenatiopsis angustata, Strigilla australis, Carditella 
polita, Mitra sordida, M. conoidalis have been collected from the 
upper beds only; and Chama lamellifera, Hinnites Corioensis, 
Hipponyx antiquatus from the lower only. It may also be noted 
that Vassa Tatei is a derived shell in the Mioceng, while, as the 
text shows, WV. crassigranosa belongs to the upper deposit, the 
junction beds in which it was found, sparingly mixed with Eocene 
species, being partly remade ground. 
By including the omitted species referred to, our quoted number 
of Eocene shells which pass up into the Miocene is thereby in- 
creased to 36 for Spring Creek and 46 for Muddy Creek ; and 
taking Messrs. Hall and Pritchard’s estimated total of 326 
species for the former, and our own of 649 for the latter, the 
calculations show that the case was in reality understated by us, 
the revised figures giving 10:1 per cent. of Miocene shells present 
in the Spring Creek Eocenes, as against 7 per cent. in those of 
Muddy Creek. A list of these species will be given subsequently. 
It is withheld just now, pending an opportunity for consultation 
concerning the distribution of a few Muddy. Creek fossils. 
In our estimate we have taken account of those Eocene forms 
only which pass up to the Miocene, but we freely admit the pro- 
priety of extending the inquiry to the Pliocene, viz., to the Dry 
Creek and Limestone Creek beds. 
