TWENTY-FOURTH ANNUAL MEETING. 



47 



any conclusion, this fact at present points to the fauna of this country at the place 

 of origin or aldainic fauna of this series. Rouilleri is probably genetically con- 

 nected with P. Dumbli, or some equivalent species, and P. oxystomum is similarly 

 connected with P. Rouilleri. In both of these, however, it is superseded in the sub- 

 sequent stages of shell growth by an acute abdomen. 



Note. — I find from correspondence with Professor Hyatt, (April 25, 1893,) that he has ascertained 

 that the genus Phacoceras is distinct from the group to which dumbli ought to be referred, and he will 

 give another generic name In his forthcoming report on carboniferous cephalapods, to be printed in 

 the next Annual Texas Report. 



THE FORMATION OF DONIPHAN LAKE, IN THE SPRING AND EARLY 



SUMMER OF 1891. 



BT E. B. KNEEK, ATCHISON. 



Though the formation of narrow lakes by rivers leaving their old courses and 

 cutting new channels in times of freshet is by no means unusual, yet in the case of 

 large rivers, such as the Missouri, these formations are never without some interest- 

 ing features. 





Prior to the present year, the Missouri river made quite a detour some live miles 

 north of Atchison, about a point known as "' Doniphan point," and each year it kept 

 extending the bend further northward, encroaching quite rapidly upon the site of 

 what was once the thriving little town of Doniphan. Time and again new roads 

 had to be cut further in from the river. But during the early rises of the present 



