BUFFALO SOCIETY OF NATURAL SCIENCES 81 



E 2022 Impression of three small ventral plates on a piece of thin 

 shale (PI. 29, fig. i). On the reverse of the small slab is a 

 fragment apparently belonging to the same individual, 

 ornamented with fine tubercles. None of these plates 

 shows the entire outHne, but there can be no doubt that 

 they belong to a small Arthrodire, probably Selenosteus, 

 their size, thinness and texture being suggestive of this 

 form. 



Genundewa limestone (Genesee); Eighteen Mile 

 Creek, Erie County, N. Y., collected by W. L. Bryant. 



Perissognathus aduncus, n. gen., n. sp. 



(PI. 20, figs. I, la, lb; PL 27, figs, 4, 4a) 



E 2397 Type. — Functional half of a right mandible, in matrix; 

 shown in outer view. Length, as far as preserved, 78 

 mm.; height at beak (about i cm. restored), 53. 



Formation and Locality. — Conodont bed (Genesee) ; Eighteen Mile 

 Creek, near North Evans, Erie County, N. Y. Collected by W. L. 

 Bryant. 



Mandible consisting of functional and blade portions (the latter 

 missing in the type specimen). Functional portion a little more than 

 twice as long as the depth at its middle; oral margin a cutting edge, 

 with a pronounced anterior beak; behind this beak a depression formed 

 by the opposing antero-superognathal; and back of this, an obtuse sec- 

 ondary cusp. Symphysis a smooth, almost flat face bent inward at 

 nearly right angles to the outer face of the mandible; its inner margin 

 ending in a row of 7 or 8 teeth, which lie in the plane of this face and 

 are directed obliquely upward at an angle of about 45°; toothed portion 

 of symphysis extending two-thirds down the height of the blade, the 

 symphyseal area below it being a more or less smooth, convex sur- 

 face. The symphyseal area shows at its upper end, lines of wear 

 which extend parallel to the axis of the beak. 



[Perissos, extraordinary, wonderful; gnathos, jaw. Specific name, 

 aduncus, bent in, in allusion to the inrolling of the symphyseal region.] 



Remarks. — This remarkable mandible clearly represents an Arthro- 

 dire of a new genus. The species is represented in the collection by the 

 type and by a beak of a mandible (E 2165) of about the same size as the 



