_'ss i ,i i.i.i i in : MUSEUM 01 COMPARATIVE ZOOLOGY, 



HoMOTKU's EL0N0ATU8, sp. nov. 



Onchometopus simplex Bassler (nan Raymond and Narraway), Maryland geol 

 but., Cambrian and Ordovician, 1919, p. 348, pi. 17, fig. 11. 



reel large for the genus, elongate, both shields subtriangular, strongly 



convex. Cephalon Bubtiiangnlar, less than twice us wide ai long, evenly 



convex. Glabella smooth, not outlined, dorsal furrows present only hack of 

 the eyee Bind glabellar furrows obsolete. Eyes prominent, situated a little 

 back of the middle but more than their length ahead of the posterior margin. 

 Genal angles rounded. 



Thorax abruptly deflected at the sides, depressed convex on top. Axial 

 lobe less than one half the total width. 



Pygidium triangular, strongly and evenly convex, the axial lobe hardly 

 outlined except at the posterior end. Exfoliated specimens show traces of 

 several ribs on the pleural lobes. 



Measurements: — One entire but much damaged specimen is about 105 

 mm. long and 60 mm. wide at the genal angles. A well-preserved pygidium is 

 44 mm. long and 63 mm. wide. A smaller one is 36 mm. long and 51 mm. 

 wide. 



This species is readily recognized by its highly convex triangular 

 shields. The axial lobe of the pygidium is also less strongly defined 

 than in most other species. 



Horizon and Locality : — A very common species in the lower 

 Echinosphaerites zone of the Chambersburg in the vicinity of Cham- 

 bersburg and Marion, Penna. and Strasburg, Va. Bassler reports 

 it from the Nidulites zone of the Chambersburg at Wilson, Md. 

 Cotypes M. C. Z. 1,577 to 1,579. 



HOMOTELUS INDENTUS, Sp. nOV. 



This species is so far represented only by pygidia but these differ 

 obviously from the majority of species of the genus in their more 

 elongate form and the upturned posterior border. The axial lobe is 

 long, narrow, gently tapering, and prominent. The pleural lobes 

 ribless, evenly convex. Back of the axial lobe the posterior margin 

 is upturned, so that in this region there is a concave border. This 

 upward tilt in the posterior margin suggests a somewhat pointed 

 cephalon. The surface of the test is covered with small flat-bottomed 

 circular depressions which are arranged about as closely together 



