, i.. \MKI.I.IHK.\N. iii.\T\ ;,;,:{ 



-ul- rr. t ! 



>. ;i. itp. 

 I'l .-. -**. 



Q0>ri.->ir./ifrjn>rur: . 1. 1 Wmi KIKI.I.. 1-71. ! ,.. vol. Iv, p. 808. pi. V. 11*. II. 



Casts of the interior tabouroabur, -trnn-iy convex, suberect. with strong erect 



scarcely incurved I -uated nearly one-fourth of the length of the shell behind 



the anterior extremity. Hack (without liinge) nearly straight; flattened sulcu- wide. 

 li^im". ' 'i'''p. vertical, causing a marked ..... npre.-sion of the anterior part of 



the umbones; usually includes one or two obscure vertical ridges. Hinge plate 

 strong, with sr Ton^ly oblique cardinal and three posterior lateral 



teeth in each valve. 







There i- no doiiht in my mind re-pectin- the -pecitic .li-tinctnos of this shell 

 and the smaller and much more al>un< hint I '. rfnn<lnln. As I have already pointed 

 out the difference, I shall not repeat them, but will refer the reader to the remark- 

 on tll;lt The next species I'. >,ir<H,,, though very similar in its general expres- 



-ion. i- not 1 I.eliove so closely related. The beaks are smaller and more incurved, 

 and there is a decided concavity in the dorsal outline behind the beaks, while the 

 anterior margin has a slight backward direction that is not seen in V.suberecta. 



formation and locality. Upper Huff limestone i.f tli.- Trenton furruatlon at Iteloit, Wisconsin. 

 28. 



NTXBMIA MK1HA. n. 

 I'l-A ! II. KIO8. B-M. 



1 small, strongly c,, n \v\. nmnded, a little the highest posteriorly; anterior 

 margin slightly ol.li.jue. dorsil outline distinctly concave behind the l>eaks. Umbones 

 of moderate si/e and promineiK-e, Imt litth- compressed, beaks incurved. Hinge plate 

 of mi..]. -.-iigth. the detail- of it- structure not well determined. Anterior 



mu-cu!ar MM rath,-, -mall, and not so strongly defined as usual for the genus. 1'al- 

 lial line indistinct except for a short distance beneath the anterior muscle. 



Thi- -pecie-, though -mailer, seems to be intermediate in its character between 

 . .VM/T*V/./ Ch-ich and I'. 1,.,,/i,,,,,, Saflord, -p. It is of more rounded form and has 

 larger and more prominent umbones fhan th.- latter, while in these same features it 

 fail- to ,.,,ual the former. The anterior muscular -ca,- ,s .smaller and unus.. 

 shallow, other ditterences may be noticed but those mentioned will, it i- b,.|i. 

 sutlice for the recognition of the q 



station and Joca/i/y^-Tn-nU.n liinwU.m'. MiniK-aimlls an.1 C.inm.n Fallg, Minnw-.U. 



n. 



This sp.-cies, ,-eem-. on the wi -en much like I. 



readily distinguished by the remarkable strength of its hinge and the great itiU-i 



