KKLATK'N <i| STHATA. XCIX 



preceding shales of the Black Uiver jjmup it thins rapidly in a southeastern direction 

 from Goodhue county, being very thin in Olmsted county and scarcely, if at all, repre- 

 sented in the southern part of Fillmore county. 



The lower eight feet at St. Paul contains great numbers of /i/gotpira rtcurvirostra 

 and Khychotrema incrtbetcent, while Pachydictya elegant Is abundant and characteristic of 

 this portion. Taking the bed as a whole the Bryoxa make up a large part of its fossils, 

 10 of the 36 species being also restricted to it Next come the Gastropoda with 29 species, 

 tho Brachiopoda with 23, and the Lamellibranchiata with 13. The principal characteristic 

 fossil* are Oallopora ampla, C. yoodtmeiuia, Prasopora insttlaria. Eridotrypa mutabili*. Stro- 

 pkomena tccflcldi, Ortkit meedti, Clitambonitt* diverta. Vamtxemia hayniana. Tetranota 

 bidanata and Arget wctenbergeiui* var. paulianut. A small variety of Pltctawbonitct aericea 

 netotenrit Sardeson) is also very abundant. Ktcrptaciilitr* otocni is occasionally met 

 with in the uppermost layers of this bed at St Paul. In the description of the species 

 this bed is always called the Galena shales. That term, however, is not entirely restricted 

 to the Clitambonites bed but occasionally includes also the lower part of the next bed. 



-pira bed. This is by far the most important of the three or four beds of the 

 Trenton in Minnesota. Outcrops are numerous in Fillmore. Olmsted, Dodge and Goodhue 

 counties, and fossils, most of them well preserved, are abundant in many of the layers. 

 As already pointed out, the lithologic character of the bed varies considerably at 

 different localities in the counties mentioned. (See sections 3, 4, 7 and 8.) The lower 

 portion only is fairly constant, consisting, wherever this part has been observed, of soft 

 shales and four or five, often irregular or lenticular, layers of crystalline limestone, 

 varying in thickness from one to ten inches. These layers are crowded with fossils 

 (mostly Bryozoa and Brachiopoda) many of which are restricted to the horizon. Being 

 a persistent and easily recognized stratum it should have been separated and given a 

 distinct name, but several reasons, chief among them the fact that we could not satisfy 

 ourselves respecting the upper limit, have caused us to refer it provisionally to the 

 Fusispira bed. Dr. Sardeson has, we believe, included it in his Camarella bed, which he 

 gives a thickness of 30 feet* He does not mention the limestone layers that occur at 

 intervals in the lower 10 or 12 feet and which lie directly upon the Clitambonites bed, but 

 characterizes the bed according to the crumbling argillaceous limestones resting on them 

 and which contain Parnstrophia hemiplicata and Cyclotpira bimilcata. The latter, as will be 

 shown presently, does not deserve to be separated from the next series of strata which Dr. 

 Sardeson calls the " Lingulasma bed." nor can we. for the reason given, justly restrict the 

 use of the name Camarella bed to the 10 or 12 feet of strata immediately following the 

 Clitambonites bed. Really, Dr. Sardeson's name must be thrown out altogether for the 

 simple reason that, according to the investigations of Winchell and Schuchert, and those 

 recently published by Hall and Clarke. t one of his supposed Camarellas proves to belong 

 to the new genus Panutrophia, H. A C.,t while the other is the type of another new genus 



It U poMlble ih.t we are mUuken and that Dr. *arda.>o really r*rd. the bed u the upper member of hi. 

 OHkMu bed (GMItambonltre h*4 of Ihta book). Afftln It I. poMlMc that thrlyr In quMtloc mtn otlrlr orrlook*rl 

 by him. ( for Utrmet. of SarriMmT* P*pn Me pp. m od xlrllof U> Inlr.lur1l,,n t., p.rt I <>f thl> rnlum*.) 

 ' PalBoaiolocjr of Sw York. vol. VIII. pi. 1 ft*-. I and II. UN. 

 < Th specie* of this KMIU are referred rovliloaally to XwntropMa In thl. rolume. pp. M. ML 



