Genii* RETZIA (King). 



The typical species of this _-> -mi- may be con-id.Ted a- in -..m- ite n-lat> ! t 



Rhynchonellldce, but more closely \ tin- fi ami in particular to the L r '-nu- x 



The shell is in general .-mall, and somewhat similar in form tn / . : . 



from hoth of which it is distinguished by the possession of calcara u- -pin -. 'I 

 turc. unlike that oi ^ . i- punctate ; hut there is not an extended hin_'e line, and th-T- 



is either no true area i.r a -mall one. The beak of the ventral valve i- j eHorate.l by a Mnall 

 foramen, and the surface is u-ually >rnamented with radiatinir stride or rih-. '11.' alh'niti. - i.f 

 this e.,.]iu- are obscure, and it is uncertain what form- should properly he rcfi-rr.<l tn it. (inly 

 One Brachiopod, VU. : /.'/:/" ./:'"</'/"'''. i llillin-s , ha- been referred t" tin- uenu.- amoiiL'-t the 

 forms hitherto discovered in the Devonian Rooks of Ontario, and in the ah-..ne.- <if any 

 tain knowledge as to its internal structure, it cannot te .-aid that thi- reference i- tr.e ir..m 

 doubt. 



107. KET/.IAI?) Ki CKMA (Billings). 



li '/. (Billii J<'U,-/i".l, New Series. Vol. VI.. p. 147. I" 



"Shell small, .-uUJobular, with from ten to twelve strung angular rihs on each va. 

 \" utial valve convex, must prominent on the upjM-r half, a -lijht me.-ial depre--i"ii the width 

 of three or four of the rihs in the lower half; beak elevated, in. -ur\ > d, hut not in contact with 

 the umbo of the dorsal valve, perforated at the point : a flat solid dcltidium or area beneath 

 the aperture. Dorsal vahe rather strongly and uuilormlv convex, mo.-t prominent alon- the 

 middle, where slight indications of a me-ial 1'old are e\idi-nt; umbo small, rounded j U-ak 

 buried beneath the lower edge of the deltidium or area of the \ cntral vahe " ( Billin-j- 



Avera^c individual.- appear.- to have a length of about four lines, with a width of about 

 the same or .-lightly less ; but larger and smaller example- are not unknown. 



I have .-een only a few detached valve- nf thi- species, and can oth-r no <. pinion a- to its 

 real affinities. By Professor Hall it is con-ider-d. with -..me doubt, as beinu i L ntieal with 



hi- Trcmal < (Pal. Net }""//, Vol. l\'.. j.. -~-> . but it i- c.-n-ideivd hv Mr. Bil- 



to be di-tinet. 



and Formation. Kan- in the Oorniferous ],ime-tone of Port 



LKIOEHTNCHTTS c Hall). 



" 



The -hel'N ni'thi- jeiiu- are ovate, circular, or tran-\ i -. . with valves unequally ooni 



and maik.d by a median ,-inus and fold in the \vntral and dorsal valv. - re-] < .'lively. 'I he 



surface is plicated bj rounded bifurcating plications whieh are always more conspicuous on 



the me-ial 1'nld and .-illll.-, whilst they ofleli IM CMliie nb-..lete oil tile lateral portions nl' the 



-hell ; cnncen trie-illy m::rked by .-tr..n- line- ,,(' .jmwth. Sub-tan.-, .,f the .-hell tihroii-. u-u- 

 ally thin. Valve.- articulating h\ teeth and BOCketSj the aj.. x of the ventral valve perl"..: 



some period of ita growth, the lower -id.- bein;_ r c'.mpleted by d.-ltidial plate-. (In the 

 interior of the ventral valve. I\M, -hml diverging <l.-iital lami-lhi- extend into and are joined to 

 the -id. .- i.r h<.tt.,in of ihe ro-trai <-avit\ ; the muscular impression OOOUpieS a narr..vv triangular 

 Or OVate-triangular Space", be], ,w th,- d.-ntal lamell.-i-. 'I'he dor-al valve ha- a well deti 



ptum, often reachini: l.-low the middle i.f the valve, and .iivided above, leavin- a triaiuular 

 >.r IpOOn-shaped d.-|.ie--i..n. The liin-.e pi-it.-, are nan-. 

 bracin- the I.eth of the ,,p|,,,-ite valv. II ,11. /',;/. \. ) \ \\ 



1 am not in the j,M-iti,,n t.. i.n ..... nnee anv opini-m a- t.. tin- validity of the L-.-HU- / 



|.niprii-ty -.' Mil- it IV.. m I; . \>< which it i- .-. i tainly n 



allied In tip- m.antitne. I -liall ac.-ept it f..r the reception i.f lli-- r..ll.'V\ 

 from the Hamilton (IioUj ral alli.-il -p. ei, - havin: ).. . n de-en' 1 ll:ill 



under thi- title IVoin the Hamilton and ('h.-mi; :nalion- 



- I.KI'.KIIVN. Mi - Ml I II > Hall). 



/ I la!! |, Thirt. . n'l. I. 1 , t ,,rt ..n tl.. 



/,'//(/'"/"/' Laura (B ' ' \ \ I 



/. Hall), j } \ : l\ l' . l.\ I I 



