THE PALEONTOLOGY OF MINNESOTA. 

 EXPLANATION OF SECTIONS 1 TO 5. 



Nos. 1 and 2, Sections of Black River group shales with the upper portion of the Stones River group and 

 the lower bed of the Trenton group. 1 was taken at a locality between five and six miles south of Cannon Falls, 

 Goodhue county; 2 at a point about one mile east of the same town. 



1. Vanuxemia bed of Stones Kiver group. 



2. Stictoporella bed, consisting of soft shales and several layers of limestone. The latter are 

 thin and largely made up of fossils, among them Stictoporella frondifera, Pachydictya foliata, Homotrypa 

 minnesotensis, Anolotichia impolita and Rhynchotrema minnesotensis. 



3. Ehinidictya bed, consisting in the lower part almost entirely of soft, greenish shales, holding 

 very few fossils. In the upper half or two-thirds there are numerous, more or less irregular, subcrystalline 

 limestone plates, largely made up of fossil remains, chiefly Bryozoa, with Rhinidictya mutabilis very 

 abundant. 



4 and 4a. Ctenodonta bed. In section 1 the lower four feet is a bed of dark shale in which no 

 fossils were observed. The upper part contains five or six irregular layers of limestone, weathering red, 

 which are filled with fossil shells, among them several species of Ctenodonta, Crytodonta tenella, C. affinis, 

 Plethocardia umbonata, Whitella scofieldi, Matheria rugosa, and numerous Gastropoda and Cephalopoda 

 The first layer contained, besides some of the species named, some plates of a large species of Carabocrinus, 

 and in considerable abundance a slowly tapering tubular fossil, between one and two inches in length, 

 that greatly resembles the Salterella billingsi which Safford regards as one of the most characteristic 

 fossils of his "Central limestone " in Tennessee. In section 5, the bed is thicker and the lower portion is 

 less sharply distinguished from the upper. 



5 and 5a. Phylloporina and Fucoid beds. These consist almost entirely of soft and highly 

 fossillferous, greenish shales. The fossils occur mostly in bands, and where they are most abundant they 

 are of ten consolidated into rough limestone layers, rarely exceeding three inches in thickness.' Bryozoa 

 are exceedingly abundant in the Phylloporina bed, and as a rule in an excellent state of preservation. 7 Of 

 the more striking and common forms we may mention Phylloporina corticosa, Trigonodictya conciliatrix, 

 Prasopora conoidea, Homotrypa tuberculata and Batostoma montuosum. In the Fucoid bed the fossils occur 

 more sparingly, and the Bryozoa are wanting almost entirely. At the top there is a rough layer of impure 

 limestone, a foot or more in thickness, which may be recognized at once by its rusty hue. It is sometimes 

 divided into two or three layers, and when it contains any fossils at all they are always imperfect. 



6. This, the lowest or Clitambonites bed of the Trenton group, consists chiefly of yellowish 

 shales. In the lower eight or ten feet there are numerous irregular or nodular layers of impure limestone. 

 These are very fossiliferous, and it is in this portion that such characteristic species of the bed as 

 Clitambonites diversus, Strophomena scofieldi, Orthis meedsi, Prasopora insularis, Callopora ampla and 

 Eridotrypa mutabilis are nearly always to be found. Near the middle of the bed Callopora goodhuensis and 

 a small variety of Plectambonites sericea are very abundant. The upper seven or eight feet consist entirely 

 of shale, and in this portion fossils are exceedingly rare. 



1. At the top of section 2, we recognized a small remnant of the Nematopora bed. 



Section 3, as exposed in an old road about two miles southeast from Cannon Falls. 



4. Ctenodonta bed. 



5. Phylloporina and Fucoid beds, both covered except at the base and top. 



6. Clitambonites bed. 6a, horizon of Clitambonites diversus; 66, of Callopora goodhuensis 

 6c, unfossiliferous shales. 



7. Nematopora bed. Drab to blue shales, including five or six layers of limestone, the latter 

 very fossiliferous. Orthis meedsi var. germana, Homotrypa similis, Pachydictya pumila, Rhinidictya minima, 

 Nematopora ovalis and N. granosa are both characteristic and common. At the point marked Cx some 

 good specimens of Clitambonites diversus were obtained, while the shales immediately beneath it, when 

 washed, afforded, beside the fossils above named, numerous minute Bryozoa of the genera Arthrodema 

 and Helopora, and six species of Ostracoda. 



8. Lower part of Fusispira bed, here consisting entirely of gray shales, quite unfossiliferous 

 except between twelve and fourteen feet above the base where about a dozen good specimens of Cydospira 

 bisulcata were found. 







Section 4, showing the whole of the Fusispira bed and the upper part of the Nematopora bed; Prosser's 

 ravine near Wykoff, Fillmore county. 



1. Nematopora bed. A layer of limestone two feet thick at the top. Obtained here Orthis 

 meedsi var. germana, a variety of O. borealis, Platystrophia biforata, Strophomena trentonensis, Rafinesguina 

 alternata, Rhynchotrema increbescens, and several undetermined Ostracoda and Bryzoa, the latter not well 

 preserved. 



