34 
MUSEUM BULLETIN No. 31. 
'Six species of Encrinurus have been described from the Trenton. 
Two of these, E. varicostatus Walcott and E. vannulus Clarke, have 
only six pairs of ribs on the pleural lobes, and one, E. rams (Walcott), 
is known from the glabella only, unless this species be identical with 
E. vannulus. Encrinurus vigilans (Hall) has nine pairs of ribs on the 
pleural lobes, but it is said that alternate pairs show tubercles. The 
axial lobe of this species is reported to have eighteen rings which ar© 
represented in the figures as uninterrupted, and there is nothing in the 
description to indicate the contrary. Likewise, the median lobe is said 
to have tubercles on every third or fourth ring. In the figure, 
tubercles are seen on the first, third, sixth, ninth, and twelfth rings. 
Encrinurus trentonensis Walcott is a little more like the present 
species. It also has nine pairs of ribs on the pleural lobes, and has 
twenty-three rings on the axial lobe, and behind them other rings 
too indistinct to be counted. Weller states that in specimens of this 
species from Hew Jersey, the rings between those bearing tubercles 
become faint and even almost obsolete in the middle. Walcott men- 
tions nodes on the first, third, sixth, tenth, fourteenth, eighteenth, 
and twenty-second rings of this species, and Weller noted them on 
the first, fourth, seventh, eleventh, and nineteenth rings. 
Prom this resume it may be seen that E. cybeleformis differs 
from its closest allies, E. trentonensis and E. vigilans , in having the 
rings of the axial lobe obscured along the top of the lobe by a smooth 
band, in the great reduction of tubercles on the axial lobe, and their 
absence from the pleural lobes. E. tuberculosus Collie need not be 
compared in any detail, as it bears tubercles in every possible place. 
Horizon and Locality. Trom the Dalmanella beds of the Trenton 
west of the Kirkfield liftlock, where the type was collected by E. J. 
Whittaker. 
Genus, Cybele Loven. 
Cybele spicata sp. nov. 
Plate XI, figure 1. 
This species is known only from a single, imperfect cranidium, 
but as it is the only true Cybele so far found in America, it is worth 
describing. 
Glabella moderately convex, its outline concave at the sides, expand- 
ing forward. Bides indented by three pairs of short but deep glabellar 
furrows which have the form of transverse pits connected by a shallow 
depression with the dorsal furrow, and their inner ends running as 
shallow furrows up into the more convex median part of the glabella. 
At the anterior margin of the glabella is a narrow furrow, in front 
