RAYMOND: SOME M.w ORDOVICIAN TRILO BITES. 285 



Hybo \>im> gen. n«>\ . 



This name is proposed for a curious trilobite in the pygidium of 

 which arc combined ih< i elongate form of the asaphid and the short 

 :i\i;il lobe of the illaenid. I know of no asaphid with short axial 

 lobe on the pygidium and only in Actinolobus among the Qlaenidae 

 ia there anj hint of elongation of the pygidium and even there nothing 

 comparable to what is seen in the form now to be described. While 

 the ascription of the genus to either the Asaphidae or [llaenidae can- 

 not positively be made until the cephalon is found, I have for the 

 present placed it with the Asaphidae. 



Hyboaspis shuleri, sp. nov. 



Cephalon and thorax unknown. 



Pygidium elongate, narrow, highly convex, turned up somewhat at the pos- 

 terior end. Axial lobe low, not sharply outlined, without rings, a trifle more 

 than one third the total length. Pleural lobes steep-sided, with narrow con- 

 cave border, which does not extend around the posterior end. No traces of 

 ribs, except for the anterior one. Surface of pleural and axial lobes crossed 

 by wavy cracks which have a course approximately at right angles to the axis. 

 Doublure wide, especially at the posterior, where it extends halfway to the 

 front, and marked by strong but widely separated terrace lines. 



M i uburements: — The largest pygidium is 73 mm. long and about 56 mm. 

 wide. The smallest is 22 mm. long and 21 mm. wide. In the large specimen 

 the axial lobe is 25 mm. long. In the small one it is 8 mm. in length. 



I know of no trilobite with which this can be compared. 



Horizon and Locality: — Only three pygidia of this species have 

 so far been found, two by Dr. E. W. Shuler in 1914 and one by the 

 writer in 1917. All came from the middle of the Holston in the 

 McNutt quarry at Sharon Springs, Bland Co., Va. Cotypes M. C. Z. 

 1,587, 1,588. 



Homotelus, gen. nov. 



Onchometopus Raymond and Narraway, nan Schmidt. 

 Isotelus (partim) of authors. 



The generic name Onchometopus was first applied (Ann. Carnegie 



inns., 1910, 7, no. 1, p. 51; Raymond, Ibidem, p. 63) to an American 

 trilobite by Raymond and Narraway in describing a new species from 



