Nineteenth Annual meeting. 129 



seven-sixteenths. If this be a true nut, the position in which it was found is re- 

 markable. Though exactly like ferruginous nodules of the neighboring coal meas- 

 ures, it cannot be sujjposed to belong to paleozoic time. It might, however, belong 

 to the Dacotah sandstone of mezozoic times. If so, it will be another fact pointing 

 towards a more eastern extension of the cretaceous formations than their present 

 outcrop indicates. Still, the writer has found a large inoceramus in a creek bed 

 eight miles east of Manhattan, and Dacotah gravel in Atchison county. Bits of 

 chalk are not uncommon in secondary drift. The distance to which such concretions 

 might be carried by quaternary agencies (or tertiary) is not easy to fix, and it may 

 be that the carriage of our fossil is nearly from the present outcrop of the Dacotah 

 formation, though how it crossed the high ridge of the Flint hills is still a difficulty. 



NOTES AND DESCRIPTIONS OF NORTH AMERICAN TABANIDiE. 



BY S. W. WILLISTON, PH. D. 



A review of my material in the family Tahanidoi has furnished occasion for notes 

 of more or less interest, and the description of a number of species which I believe 

 to be new. This material, including one hundred and ten species, has enabled me to 

 identify with assurance most of the known species — a task that has been greatly 

 lightened by Osten Sacken's thorough work in this family. 



It is of interest to note that, hitherto, not a single one of our species in this fam- 

 ily has been found identical with a European one, a statement that I think cannot 

 be made of any other dipterous family of any size. The North American T. jiavipes 

 Wied. has, it is true, been discovered from among specimens from the Amoor in 

 eastern Siberia, by Brauer, in company with a species common to Europe; but this 

 is, I believe, the only known instance in which the habitats of any European and 

 American species have been found to be anywhere in common. 



The characters given by Osten Sacken for the disruption of Tabanus into the 

 smaller groups, Therioplectes and Atylotus, though of importance, are insufficient, I 

 believe, to warrant their use as generic characters. The genus Atylotus, Osten Sacken 

 based chiefly upon the absence of the ocellar tubercle and the presence of ocular 

 pilosity, but that he did not accept these characters himself as the chief generic dis- 

 tinctions is shown conclusively by his final location of T. Rheinwardtii Wied. and T. 

 cerastes 0. S., both with the above-given peculiarities, under Tabamis sensu stricto. 

 On the other hand, other minor differences given for this genus Brauer states are not 

 applicable to the European species. In some cases the ocellar tubercle is a distinct 

 and easily appreciable character, but in others it is nearly or quite impossible to 

 decide whether a given species has or has not such a tubercle. Certainly, in my early 

 experience in the use of the table prefixed to Osten Sacken's Prodrome, no character 

 was a greater source of doubt to me than the present. The character, moreover, is 

 a sexual one, the ocellar tubercle being present in males where it is absent in females. 

 For these reasons I have rejected Therioi^lectes and Atylotus as genera, though the 

 retention of the names is desirable as expressing in many species certain definite 

 groups of characters. 



As usual in collections, I have but few males for comparison, but it is possible 

 that a character of some value may be found in the claws, pulvilli and empodia. 

 Whether they are enlarged in all males, I do not know; certainly they are in many. 



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