Maryland Geological Survey 495 



Genus HOMALONOTUS Koenig 

 HOMALONOTDS SWARTZI D. sp. 



Plate LXXXIX, Figs. 10-12 ; Plate XC, Figs. 1, 2 



Description. — Cephalon unknown. Thorax very broad, trilobation obso- 

 lete, axial portion broadly arched, pleural portions steeply descending; 

 segments curving gently forward in axial portion ; posterior portion of 

 each segment broad axially, tapering gradually toward fulcra; transverse 

 suture of each segment of nearly constant width, a narrower and less steep 

 secondary suture anterior to and parallel with the primary ; pleura bend- 

 ing suddenly downward at fulcra, the transverse suture curving forward 

 distally, leaving the posterior portion of the segment very broad. 

 Pygidium large, subtriangular in outline, lateral margins at base nearly 

 rectilinear, posterior extremity not seen ; faintly trilobate, the faint longi- 

 tudinal furrows making with each other an angle of about 40° ; axis very 

 broad, depressed, annulations ten or eleven, low and broad, arching broadly 

 anteriorly; pleura? profoundly arched along fulcra and incurved at base, 

 each bearing ten annulations which are broad, low, nearly direct, and be- 

 coming obsolete distally. Dimensions of pygidium : Length about 82 

 mm. ; width 72 mm. 



A cast of a pygidium, which is taken as the type of the species, was 

 discovered by Dr. C. K. Swartz and is named for him. In size this species 

 is comparable to H. major Whitfield. The above incomplete description 

 of the thorax is from a single thoracic segment from Miller's Spring, West 

 Virginia. The pygidium and the segment presumably belong to the same 

 species. Both occur in the Oriskany, and are of large proportions and the 

 fulcra are of about equal sharpness. 



ccurrence. —Oriska'sy Formatiok, Eidgely Member. Sand quarry 

 4 miles southwest of Hancock .(pygidium), Maryland; Miller's Spring 

 (thoracic segment of glabella), West Virginia. 



Collection. — -Maryland Geological Survey. 



[Ohern.] 



