I ) 



cardinal angles ; dor.-al valve v rv mo h-rately concave or nearly flat. The .-url'.a , i- mark.-'! 

 by from twenty to twenty four simple, sub-angular ribs, some of which are occasionally bifur 

 cated towards the margin, and which are separated by interspaces wider than them.-elves. ID 

 the eared examples the ribs are obsolete towards the cardin.il angles. " The cardinal margin 

 shows two and rarelv three spines on each side of the centre, which are abruptly bent outward- 

 so as to lie nearly parallel to the hinge lim-. and the outer one extending much beyond tip 

 cardinal extremity. The area is very narrow,' (Hall). 



Some of the points mentioned in the above description I have 

 not been able to verify from ourspecimens. a> they are mostly imp'-r 

 ^^^ ' feet. Thus, [ ha\e never seen either a dorsal valve, or a ventral 

 valve exhibiting the .-pint -. Upon the whole, however, I have no 

 doubt but that our specimens are truly referable to < '. 

 as they agree with Halls description of this species in all essential 

 charaet.-r-.. MI far as observed. As occurring in the M.nv, llu> 

 Shale, the ventral valve is stated by Hall a.- U-in- only slightly 

 convex or nearly flat ; but as occurring in the Corniferou- I, me 



a. f '. natural j TI -r .. . \ f . .11 



. en- stone and Hamilton group, it is said to be ''often quite gibboua 



""- Our examples agree with the latter in this, and only differ in hav- 

 i from the Comiferoua . i- i i 111- i 



of onuiriu. Neural ing the cardinal angles more or less produced and salient a phe- 

 nomenon, however, which Ball states to be of occasional occurrence. 



The species is nearly allied to ' </,//.-/ i Hall), and the two are, perhaps, only varieties- 



lit a single species. 



Locality and formation. Kather abundant in the Corniforous Limestone of Kama - Farm. 

 near Port Colborne. 



90. CHONETES HE.MISIMIERICA (HALL). 



t h,>n'i.<i>lnri'-n (Hall), Tenth Report on the State Cabinet, p. 11''.. 

 Chonetes hemupheriea (Billing;, Canadian ././////<//, New Series. \'ol. VI. p. -"'l 1 .'. 1 

 121-123. 



11 .11), Pal. N. Y. Vol. IV. PI. XX. Fig. 6. 



Shell semi-oval or semi-circular, the greatest width being alun- the hin^c line. Cardinal 

 - u-inily oonsiderably produced and auriculate, sometimes reflected. Ventralvalve ' 



.e\ and ventri<-oM-, depiv--i-d in the neighbourhood of the ear-, and sometime^ shnwiii_' ;i 

 shallow mesial depression extendm- toward- th" front from the beak. Umbo very prominent. 

 incurved, the area lii-in- often inverted, or brought under the body of the shell at r 

 angles to the plane of the mar-in " ( Billings *. The area has a width of about half a line, and 

 i- obliquely striated, whil.-t it- outer mar-in carries the base- of from three in fnur small -pitn^ 

 on each .-id.- of the umbo. whicli, however, appear to lie very rarely piv-erved. l'or-al valve 

 concave, followiiu the ventral valve, but with a concavity le.-s than the eon\exily of the latter. 

 Area of the d'H'-al valve narrow and almo.-t linear, marked with a row of small tran-\er-e de 

 : -ions or pits, which are mo.-t o(,\iini- ip-ar the nmbo. 



Sui ! H'.. marked with radiatin-. munded. -imple ril'-, which become ob-ol.'te on t! 

 A few of the ril'- bitureate. 'J'h.-re are from four to |i\,- ril,- in tlie SpaOfl "f one line, and 

 thi y a]'. led by inti-r-pae--^ about equal to their o\\ n \sidth. 



The dorsal val\e () f thi.- -peeie- appear- t., be eztremelj rare, Hall ha\in- never ol 



it. and Killin-- ha\in- 8880 but t\\<p tra-jmeiit-. I have milv come BOTOM a -in. le -peciiip n 

 whi'-h exhiliit- th- interior. Thi.-. example .-how- tin- e anlinal prOCeM t ..... n-i.-t of two m 

 parallel and clo.-e|y eonti-iioii- ili\i-ion-, each of \\hieh is hifnl at the tip. h'roin the : 

 of the (irdinal prO06M i- emit inued a rm--ial rid-e. which die> a\va\ towar-i- the tVont o| the 

 iheil ; and mi either .-ide i,f thi- are iwo di ver-in- rid-e, which coalesce with tin- pr.-.-. .i 

 the base of the cardinal pmct-.-s. The radiating rib- are jn-t a- e.-n^pii -11011 - in the in'.' M. 

 externally, and are marked by minute remote pu-tule- arran-ed in a >n each rib. 



Tin- mnJOolai impre noni cannot be made i.ut. 



I'/ . i- readily di-t in-ui-hed 1 I ral I'.. rm an 1 r 



tion. The lai iineii I ha\e leeO ap|.ear- to be about ,-ixte, n line> almi- th. h : 



by twelve lines iii len-th ; but a\. i . I mplefl are ..im-what -mailer thin t: 



/ Hare in tin- ( '..rnif.Toii-. Lime-ton.- ,.( 1'i.rt Colborno. . A I < 



in the Si -boh a rii- (irit and ( 'oriiiferoii^ Liiue-tune of tin- State of N.-\v York. ) 



