OA- IDA 



citically. A itiili.i ilillers from K.ixthmi in the lesser prominence of the 

 ' .-SB or inexperienced observer mi^ht confuse it with the associ- 



ated Tftninnfn liidnrsntn, yet any one accustomed to the work of discriminating 

 between fn^iU can M-an-dy fail in separating them at once. 



Formation and locality.- CllUmbonlte* bed of the Tr.-nt<m k f roiip, near Cannon Falls, Minnesota. 

 CWfcrt*on.-E. O. fir: 



Genus BUCANIX. Hall. 



(pan H .Pal. New Y..rk, vol. I, p. :ii WAAOBN, 1880, Pal. Indira, scr. 13, pt. 2, 



1.10- ISO. KOKKN, 1889, N. Jahrburb f. Minoraldk'i'', '-I' 1 ., Hfilaj?eband 

 rl, p. 379. 



1 Or ^enenc characters see page 850. 



A- originally defined by Hall, this genus was to include bellerophontid shells 

 having a large utnliilicus. For many years the genus was regarded as of very 

 doubtful value, paleontologists having learned that the relative size of the umbilicus 

 was not of itself sufficient ground for a separate genus. The fact that the original 

 types of Hm-tinia hail revolving lines was not considered of consequence by Hall in 

 1847, nor by any other paleontologist who had occasion to refer to the bellerophon- 

 tids previous to 18SO. In this year an important work on these symmetrically 

 involute shells was published by Waagen (op. ri'/.). This author proposed to apply 

 the name Bucania to all bellerophontids possessing revolving stria-, and he redefined 

 the genus in accordance with his view. 



While it is not to be denied that Waagen's proposal was a decided improvement 

 upon previous attempts, it is still evident that his arrangement is artificial. Ili- 

 iletinition is too broad since it includes a variety of types that, while agreeing with 

 the originals of linrnnii in having spiral lines, are nevertheless widely removed from 

 them genetically and readily distinguished by other characters. Lines of one kin<l 

 or another, having a spiral direction, occur not only in species of the type of /' 

 sulttitina. hut in Salpingostoma and Trrtnunotus and in the new genera Cyrtolifinn, 

 'ii anil Tflrnniifa. Then they occur in the very best development in a large 

 group nf -peci. -ing in time from the Trenton group to the close of the 



Paleozoic age, which we have decided to separate as a new genus under the name of 

 Huctinopfi*. 



The trouble with littrnnin has been that its real peculiarities have never been 

 appreciated. Hall, as stated, regarded the large open umbilicus as ilUtinctive for 

 the genus. His description says al-<> that the mouth i- abruptly expanded, but in 

 tin-; doubtless he was influenced by hi- /. which now is not a Ilwinin hut a 



X'il}'ingostoma. The name of the genus was most probably inspired by the same 

 species, and if it bad been customary at that time to designate the type of a genus his 



