134 PALEOZOIC PALEONTOLOGY. 
eurekensis Walcott, from the Pogonip limestone of Nevada. The 
New Jersey species attains a larger size than any of the others, 
judging from their published illustrations. It differs from J. quad- 
ratus Hall in its less quadrangular cranidium, its proportionally 
narrower free cheeks and in its much more elongate pygidium. From 
I. convexus Whitf. it differs in having more prominent eye-lobes, in 
having a broader cranidium anteriorly and in having a much more 
elongate pygidium. From J. dia Wale. it differs in having a more 
elongate head, with narrower fixed cheeks in front. From J. ewrekensis 
Wale. it may be distinguished by its more pointed and narrower 
cranidium anteriorly and by its somewhat narrower free cheeks. 
The pygidium described as Asaphus convexus Cleland, from the 
Beekmantown limestone near Fort Hunter, New York, is evidently 
the pygidium of J. columbiana, and if Whitfield had not already de- 
scribed a member of the genus under the same specific name, Cle- 
land’s name would have been adopted. Associated with the pygidium 
called Asaphus convexus is an imperfect cranidium, which has been 
briefly described and illustrated by Cleland under the name Bathyurus 
sp.? This cranidium, also, in all probability is an incomplete speci- 
men of our J/lenurus columbiana. 
BATHYURUS? sp. undet. 
A single specimen of a small, pustulose, trilobite glabella has been 
detected in the Beekmantown fauna from near Columbia, which bears 
some resemblance to Bathyurus conicus Bill., as illustrated by Whit- 
field,* from Beekmantown, New York. The New Jersey specimen 
is only 3 mm. in length, however, which is about one-third the size 
of Whitfield’s specimens. Another similar species is Bathyurus ellvp- 
ticus Cleland,+ from beds of similar age near Fort Hunter, New 
York, but the New Jersey specimen is also smaller than this species. 
* Bull. Am. Mus. Nat. Hist., vol: II., p. 61, pl. 18, figs. 15-21. 
+ Bull. Am. Pal., No. 18, p. 17, pl. 16, figs. 5-6. 
