JOURNAL OF PROCEEDINGS. 155 



to the base of the corresponding exterior, and the pairs of petals to that 

 of the inferior sepals ; the 8 organs forming rather one than two cycles. 



How these female plants, as they must be called, which, this spring at 

 least, form the immeasurably largest part of the whole crop, can be fertil- 

 ized by the few complete ones growing in the neighborhood, is not easy 

 to understand. 



Does not this dimorphism obtain in other species of this genus, in Le- 

 pedium and other Cruciferce, and would not several so-called species fall, 

 if correctly understood, under other fully developed ones as incomplete 

 forms? 



Dr. Shuniard submitted the subjoined vertical section of 

 the Silurian Strata of Cape Girardeau County, Mo.,* con- 

 structed from observations made by him while connected 

 with the Geological Survey of the State, the same being 

 an abstract from his Report made to Prof. G. C. Swal- 

 low, State Geologist. He remarked that in the adjoining 

 county of Perry the rocks of the section were surmounted 

 by beds, of the age of the Onondaga Limestone, containing 

 Favosites hemisphcerica, F. basaltica, Acervularia rugosa, 

 Zaphrentis gigantea, Spirifera undulata, Atrypa reticularis, 

 Phacops, Dalmania, etc., and which lithologically corre- 

 spond very closely Avith the Shell beds of the Falls of the 

 Ohio. 



May 6, 1861. 



The President, Dr. Engelmann, in the chair. 



Eleven members present. 



Letters were read from J. T. Irwin, Ravenna, Mo., April 8, 1861, send- 

 ing list of trees in Mercer Co., Mo., and offering exchange of specimens 

 of fossil shells; Mr. Senoner, Wien, Nov. 8, 1860, concerning receipt 

 and distribution of Transactions of the Academy; Acad. Royale des Sci- 

 ences, Stockholm, Nov. 18, I860,— Roy. Pruss. Acad, of Sciences, Berlin, 

 Oct. 18, I860,— Naturf. Gesellschaft, Bamberg, Dec. 15, 1860; Accad- 

 delle Scienze dell' Istituto, Bologna, Feb. 4, I860,— Konigl. physik.-okon- 

 om. Gesellschaft, Konigsberg, Nov. 19, I860,— Dr. D. F. Weinland, Frank- 

 furt a. M., Nov. 7, I860— Senkenbergische naturf. Gesellschaft, Frankfurt 

 a. M.. 9 Oct. I860,— Physikalisch-med. Gesellschaft, Wiirzburg, 23 Jan. 

 1861, '& Nov. 5, I860,— Royal Danish Society of Scien., June 1, i860,— K. 

 K. Akad. der Wissenschaften, Wien, Nov. 28, 1860, acknowledging receipt 

 of the Transactions of the Academy and sending; publications in exchange ; 

 Hon. Samuel D. Bell, Manchester, N. H., April 23, 1861, ordering Vol. I. 

 of Trans, of the Academy for the city library. 



The following publications were received : 



Bulletin of the Wisconsin Agricul. & Median. Association, Milvvaukie, 

 Wis., 1860. — 2d Ann. Exhib. of same, 1861, from the Association ; Jour. 

 Franklin Instit, Philad., Vol. XLL. No. 4, 1861, from the Institute; Proc. 

 Acad. Nat. Scien., Philad., March, 1861, from the Academy; Fr. Ambrosii 

 Flora Tirolias Australia, Vol. I. Pt. 1-5, Vol. II. Pt. 1-3, from Mr. Seno- 

 ner, Vienna; Royal Soc. of Sciences, H.mdlinjrar, Band II. 2, 1858, Stock- 

 holm, — Fregatten Eugenies Re*a, 1851-53, H. 7, Zoologi IV".,— Meteor. 

 Iakttagelser i Sverige, af Er. Edlund, Bd. I., 1859,— Ofversigt, 16 Aug. 



* For Vertical Section of Silurian Strata, see next page. 



