and the anterior extremity of the mesial septum. The cardinal process, seen from the inner 

 side, is bilobed, and from the exterior side .each of the.se divisions is usually bilobed. 



"These shells differ from i>7/'- />/////<>.</ in the extremely narrow linear cardinal area, 

 greater extension of the hinjre-line, more extreme arcuation or ventricosity of the ventral valve 

 in many or most of the species, and especially in the direction and termination of the renilbrm 

 vascular impressions, which resemble those of Auloxt- / }, and of ,-oiue species of jProductus. It 

 differs from /'/<///<'//.< in the constant presence of an area, hin-c-t. th, and socket.- " (Hall, 

 Pal. New York, Vol. IV., : 



friHlwt'-llii is considered by Hall as a mere sub-irenus of Pro<lni-ta, but it seems to me 

 that the articulation of the valves by distinct teeth and the presence of a di-tinet hin-e-aiva 

 are quite sufficient characters to -eptrate Prodltctetta L r '-ii.-rically fro in /', / /,/. Whether 

 J't'o'/iii-fifln can be kept apart from Strophe > f Kin- i- another matter, the chief oharaol 

 by whieh the two are separated beinir merely i|ue-tion- of de-n-e. In external appearance. 

 however, the shells referred to l'i-<><l<i<-ti'll>i resemble /', . much more nearly than do tii 



referred to .>ti-ujifni/<>.<ni. 



Professor Hall has described many species of /'/W//,7.7/i/ from the Devonian Rock- "t 

 the State of New York, chictlv frun the Hamilton and ('ln-iimn- jroups, but also I'mm the 

 ( 'orniferous Limestone. I have only met with a single form of the -run- hi the Devonian 

 form ition of \Ve.-tern Ontario, and this, though exceedingly abundant in the (.'ornifcrou* 

 Limestone in several localities, is certainly distinct fn>ui any of those recorded by Hall. I 

 shall, therefore, describe it a< ne\v. under the name of Productetta l'.n,n.<is. 



93. PRODUCTKI.I.A KUII.N-IS (Nicholson). 



Shell minute, thick, semi-oval or nearly semicircular, the length about one fourth 

 than the width as a general rule. Hinne line as wide as. or wider than, the -ivate-t width of 

 the shell; the cardinal angles rounded, or, more e.unmoiily. distinctly auriculate. 



\ ntral valve exceeding! v gibbon- and vciitrico-c . stroiuiv and rejularly arched frmn the 

 beak to the front margin, but depiv-.-ed tow aid- the cardinal angles. Umbo obtuse, prominent, 

 htron-ly incurved. Ar.-a very narrow and difficult to make out. The cast of the ventral 

 valve exhibits a longitudinal -lit extending from tin- beak about one fourth or One-third of the 

 ! i_th of the >hell, and indicating that the cavity of the beak was divided b\- a low mesial 

 p-'.rtition ( ' ro-tral septum ";. In front of this -lit there is nit en a hi>i>e.>hi,e >hape.l d. \ at ion 

 rcpiv-eiitiii'_' tin- oast "t tli'- pit to which the divaricator nin attached, but thi> can- 



not a, \\ a\ - be made out. (Jiimn'or bulb sides of the ine-ial slit there is al0 generally 



hti-r and shallower groove bounding tin- nmbo latcra.lv . but the -eneral .-urface of the . 

 i- ijuite -mouth and not jiitti-d. 



Dorsal valve dcpres-cd cnnVAZ, not <_ r il>h''U-. dej ro.-i-d \\\ ard.- the cardinal an -lev When 

 partially dcci ,rt ieatcd. tin- ,f r~i| valsc shows very ''i-tinc, i\ fr-mi six to ci-hi c.in.-eiitne 

 imliricatiiiL' line- of -ruwtli. In tlii- eondition it al.-o cxliibiis a ni"re m- le-- d. lined median 

 Inn-itudinal rid::i: which extcn.l- IV,, m a -mail, but ei-n-lant e|,,irjaled pit, |,lae.-d ju-t in Iront 



of the nmbo. to the front mai-'jin two generally -trmijer ridges diverging outwards, one on 



:i -idc ,,f the central line, frnm the umb,. toward- the mai-jin. 'I'he beak nf the ilnr-al 

 \alve i- .-can-ely prominent, \\liil-l th, iv i- an cxtri'in--ly narrow linear area, and a -mail car 

 dinal proc, 



'I he interior of tin- il.r--d valve .-\hibit- radi it in- lin, - ,,f mini.te I'lon-at.'d pit-, \shich 

 cover it- wh',;,- -urlace or ar,- m.,-t abuml ant in tin- c, ntral |",i timi nf the valve, and dimini-h 

 as the mai_in i- appro-iehcd. l!<--iile, th,--,-, ,,n eitln-r -ide of the midille line an- t 

 of deep, slightly Curved -u oi, which extend from beneath the beak to near the mar. MII T ! 

 of the innenno-t pair are m,,-t . on-tanl, and are pi ie,-d ijuit.- olofte to the central line of the 

 val\e Th,.-' of the oiitrr p,ir ar. more \ariabli-, and tin-re an- oftrii two or thiv,- ridiatin- 



grooves on either side in p toe of onlj one Immedi th the beak, la-tl\, ar. 



two ' on,- , h r-M-li -i.li-. wliicli on \ ,h\, : hil\ from the direction of the 



liinjj'-.line, and cxti-nd mil \ a -hoi I ,|i-ianc,- into the -hell 'I'lii'-c are a|>pai,-ni 1\ >\> ntal 



The -in'facr of the V, ntal \al\e i I but ap| b,- .jiilte -mooth . th-- 



rorfaoe of the dorsal valve exhibit* fui ni conci-ntrie -tri.-i' v. radial e can !< untie 



out; nt.r are ther.- an;, of -pm,-- citln-r on the bin in n in of tin 1 Ventral \ 



ilpun i '';> -ui lac,- ,,f ,-ilh,-r \ai\e. 



