117 



smaller than the typical forms of P. diimusunt, and also carries much fewer spines. Upon the 

 whole it seems to be most like P. dimatum, var. />///.,////< ^//j. Hall (Fifteenth Report on the 

 State Cabinet, . 38), though it never appears to attain anything like such a si/e. It al 

 somewhat resembles P. dumosum, var. atttnua/um. Meek (Paleontology of Ohio Vol I 

 PI. XX., Figs. 2 a, b.) 



The shell in our specimens is always of small 

 never appearing to exceed three quarters of an inch 

 in length, and is composed of about two volutions. 

 The apex is small, closely enrolled, and in contact 

 with the body-whurl till close to the aperture. The 

 body. whorl is greatly expanded, the aperture patu- 

 lous, oval, or rounded, with a diameter of about half 

 an inch, and having the lip strongly sinuated. The 

 ^ surface is marked with fine close-set tran-vcr-- striaa, 



which are stronger and are undulated towards the 

 aperture. The body-whorl carries eight to twelve or 



Different views of a sm;ill I'lati/cerax (P. tl' i 1 i i , . 



..a the Hamilton more strong tubular spines, which are arranged in 



/,-. 



Xatur.i somewhat irreuular longitudinal lines. It is quite 



possible that our shells are new, as they do not appear to correspond exactlv with anv previ- 

 ously recorded form ; but, in the present condition of the genus /'/<////,,,,. it would be 

 unsafe to give it a separate title. 



L' ' -/ /'////<<///". Common in the Hamilton Formation, Arkona, Township of 



Bosanquet. 



Genus PLATYOSTOMA (Conrad). 



The shells of this convenient but hardly definable genii- are ventricose. witli a short, 

 deprc-M-d. or very moderately elevated -pire, and an extremely exp m 1 i body-whorl. The 

 aperture is very large, and the columellar lip thickened. 



Specimens which appear to have all tin.- characters of P. r,ittri<-".<<i (Conrad), from r 

 Lower Helderberg and Ori.-kany Sandstone, arc not uncommon in the (' ,>niiteniu- lin. 

 of Ontario ; but they occur entirely in the condition of ca-t>. and do not, tlierefore, permit of 

 anything further than their mere identification. 



1-14. PLATYOSTOMA VKNTHICOSA (Com- 

 1'late II., Fig. 4.) 



1 'onrad), ./. /. Nat. >' . P) - ' V \ 1 1 1. 



P. 275. 



/'' I (Hall). Pal. \. )'.. V..1. III., p. 300, PI. LV.. and p. 169. I 



XII . CXIII. and <\\. 



>lii-ll L'lobM-.-, .,] dcpr- -- d J..IMI-C. and nfteti obliijiicly ovuid. var\in_' in Conn. Spire 

 moderately rlc\at.-d. (nn>i.<tiii'_ p [ three or lour volutions, the ia-t of u l.i.-h i- i-xtr. in< 

 tricu-r : volution- flattened npi.n tin- upper -id-- ; apiTture circular or MI). .olmnellar 



lif) nfli--.. id - . 06 marked by tine cln-rlv arranged .^triii 1 parallel to the iin. ,- d' urowth." 

 II - . .'.. p. L< 



Cast- appan nily belonging to tlii- ~p, cjc- ari- f'.ir tV-m uiici>:iiiiio!i in the Corn: 

 Limestone 01 Omario. ami I hav !i. Hi' d one n|' tin- be-t that I have .-ecu ( Plate II.. ti_' ' 

 In torni and dim> n-i"n- tin- >].cciincn- ditl.r OODBldorablj, but thcv all aL r rec in the 



elevated -pin-, v. niric.,-,- h,,d\ wln.rl. and -imply -tri.it. d surl 1 '-n 



:red ha- t he body wlmrl ! . llnw tlian i- UMial in thi> -j..-c ured by Hull, 



and it- dimension* are a- fnlli.w-: Ibi-ht nni- inch and a half in reality -<m< -what O\ 

 tin- ' ; breadth two inchc- ami t\\" lim-- licj-ht ol' ap- rlun-. -ixicen lim - . width f .i[- i ture. 



mi i -n li'.. -. If SJDJ of the examples, however li-i\- -'lim. : -nailer than th 



/. ' '// <nl i ,,.,., |. MI1 . Port ( .i"-niiv 



Hdl). 

 Sln-11 witli a d'-pn- t d r m-.'I.Tat-l\ ( -| : n.I an . \pind., 1 ami vcntrioOM 



