72 KEW PALEOZOIC VERTEBKATA. [Feb. 5, 



and I have endeavored to identify among them the species of 

 authors. The H. granulatus of Newberry appears to be based on an 

 inferior side of a scale of some species, whose true characters will 

 remain unknown until the superior face is discovered. The follow- 

 ing species seem to be well founded, and to differ as follows : 



I. Basal part of scale smooth. 



a. Ridges entirely broken up into tubercles 



H. tuberculatus Newb. 

 aa. Ridges partially broken into tubercles . Z^. gigajiteus Ag. 

 aa. Ridges not broken into tubercles. 



Ridges moderate, inosculating, no intermediate tubercles 



H. nobilissimus Ag. 

 Ridges moderate, inosculating, small tubercles between the ridges 



proximally H. dewalkei Loh. 



Ridges moderate, not or little inosculating \ no tubercles 



H. americanus Leidy. 

 Ridges moderate, parallel, no tubercles, small.. ZT. radiatus Newb. 

 Ridges very wide with fine grooves H. hallii Newb. 



II. Basal part of scale with rows of tubercles. 



Ridges subparallel ; tubercles it\N, in a small tract ; size small .... 



H. flemingii Ag. 

 Ridges coarse, inosculating, 25-30 ; tubercles less numerous, in 



25-30 rows ; large H. i?iflexus Loh. 



Ridges fine, inosculating little, 40 ; tubercles more numerous, in 



about 40 rows ] large H. serrulaius Cope. 



III. Basal part of scale with coarse radiating ridges. 



Distal ridges coarse, numerous, interrupted, passing gradually into 

 the rather fine, proximal ridges which are not cut by cross 

 ridges ; large H. filosiis Cope. 



IV. Basal part of scale with fine radiating and concentric ridges 

 (Glyptolepis). Size smaller. 



Distal ridges coarse, few, closely placed, without lines between ; no 

 radiating lines of tubercles H. latus Cope. 



Distal ridges coarse, more numerous, closely placed, without lines 

 between; proximal radiating lines of tubercles, forming a fan. 



H. flabellatits Cope. 



Distal ridges fine, with thread lines between, proximal radiating 

 lines of tubercles H. leptopterus Ag. 



