91 



the two species can be ^enericully separate!. /,. ///// , . , i- distinguished from /. 

 i by its much more elongated ami contracted form. th . r convexity of its valves in 



the umbonal region, the much more prominent .-ui'l -troiuiy incurved beak of the ventral val\.-. 

 t'ti' ab.-'-nce i'f';i foraim-ii. the much irreater width ami ahallowneSB nt' the -inn- and fold. ami 

 tin- -t n>n ire r and more crowded line- of irrowth. I liave not -,-en anv example which exhibits 

 thi- interior. 



L :<iHt>i inul /'-////<//''"/'. --Shale.- of the Hamilton Group. Widder. Town-hip of lio.-ampuet 

 1 llected by Mr. George Jennings Hind 



Gem/* AMI-HH. KM \ i Hall;. 



Shell ineqaivalve, oval, ovoid, or sab-triangular, more or le>- e >nvex or uihboii- with- 

 out mc.-ial told or sinu-. Valve.- articulating by teeth and socket-, witlmut area. Tin- d'-\i 

 tal lamella) in the ventral valve conjoined on their dor>al ,-idi-, tiinuinir an angular tr.>u_ r h or 

 pit. which open.- exteriorly by a triangular ti-.-nr.- 1> n^ath the beak, and in it.- antrrinr ext-n 

 .-i"n i- supported on a central septum. Dorsal valve with a >tr"ir_' thickem-d cardinal prOO 

 or hiutre-jilate. bm-dei-ed by the teeth -ucket-. anchylosed to the b .ttmn of th- val\ -up- 



]'r;ini: the crura, which extend into the cavity of the shell ' i Hall, 1'al. N. V. \'l. 1\'., p 

 36. 



In addition to these character-, there is a foramen which extend- beneath the bin 

 plate of the dorsal valve, and ends in a perforation ;;t the beak, and the >hell-.-tructure i- di- 

 tiiietly punctate. 



Hah In- -eparated the genus Ainj>hi<j< /tin from Sti'n-U/nnl/nin ( IlilliiiL'-) t" include tin 

 .-iirje - nitn | =: I'u't'ii 'ii'jntiix. \'ann\i in i. np'pn the 'jn.iind that thi.- 



JSee ii" area in the ventral valve, with a foramen in the di>r-;d valve and a pune- 



-hell -tructure. ( >n the other hand, tlie typical speoiefi of S-r-/cltiitiit 



in the ventral valve, a -mailer angular jdt. no foramen in the dorsal valve, and an impum-tat- 

 ami tibrou- -hell -tructure. Without entering further into the controver-y which ha- 1 



ied on a- r-.-jard- tlii- i|iie.-tion. it ma\ l,e -aiil that the-.- difference- appear ,-utlicient to 

 entitle .1 niji/iii/i ni'i to IK- con-id. -red a- di-tinet. if not ^em-rieallv. at any rate -ub _eneric.dly 



s linia ami /'. ntanu /".-. 



From /'./<>>/"//'. in -|.it'- of -re-it resemblance in e.\t,riial form, and al-o id- 



BOme point- of internal -tructure, the -eim- . I inji/ii</. .- i- -e].ar-ite,l l,y the angular pit mad' 

 li\ the conjoin, d denial lamella- of the ventral vahe. and by apparently having tree crura in 

 the dor-al valve without appenda. 



The only -; : tlii- genUfl known in ( 'anada, i- the Am\ "I the 



( 'c-rnil, roil- Lime-tom-. 



1]H. A \i I'llli.i.si \ BLONQATA ( Vanuxciii). 



/'/' \ innxem), Report Third i;.-ol. |)i-t. N, w V.-rk, p. \\\'l. 



.!/ I lall ,. 'I'eiiih Report on the State Cabinet, p, IL.';;. 



Hal. .. Pal. \. } ,' . \ of 1 1 1, p i 

 i; .: i, ,/,,,, ,-/.:!/. \'ol. VI.. p L'I', 7. ti 3.91,92. 



II /' A. ) .. \ o|. |\ ., ,, 383, I'l. I, IX. 



Sludl very \ ariable in I'm m. generally >te oval, -.mitime- QTatO, the 1.' 



tin.-- marl', lui.-e th>- width, or the tuo diameter- at other time- DOarl) Oqil 



i.;. em !r, nt point,,!, rounded, or Mibtium 1\. 



'i,-ral Hi' ' Inn ll.- ' n oblii-i-l V earin if. | 



Uppi-r hall ; the b.-.ik ilielirv d o\,-i the limbo of tl,. I 



lie than the Tcntral. oft. n . the middle lin, in it- upj-i halt, and -1, 



.Hi, I li-.nl. Sllll.iee i, ),, |,ut mai kt d wilh -' 



' i le i i'L',- and KP .\\ I h I n ; I" exhibit 



flatten, d ' i . Lei individual < 



width ten line |. :ndi\ idual- :.,m t\\o to ai much a- |,.ur inehe- in hn^lh. 



