210 
PALEONTOLOGY OF NEW YORK. 
type specimen has been broken away, removing the summits of the posterior 
plates and covering the spot where the scutum and tergum would normally lie. 
The specimen, which retains the replaced substance of the original shell, 
shows an expanded margin about a portion of the periphery, and this prob¬ 
ably represents a portion of the edge of the valves which has been flattened 
and creased by compression. 
Dimensions. Length 4.5 mm., greatest width 3.5 mm. 
Observations. This minute species is the only known representative of the 
Balanoid cirripeds in the PaliBOzoic rocks, with the exception of Balanus carbo- 
narius, Petzhold, from the Carboniferous rocks near Dresden, Saxony (Neues 
Jahrb. fiir Min., etc., 1842). Protobalanus, however, differs essentially from 
other forms which are included in the order Balanidce in its great number 
(twelve) of plates, the usual number being six, four or one. This fact is not 
without significance, as it may indicate a greater specialization and a higher 
degree of structural development than in the other fossil and recent species of 
this order. 
Distribution. Hamilton group. In the Marcellus shales; Avon, Genesee 
county. 
PAL^OCREUSIA, N. G. (J. M. C.). 
Pal^ocreusia Devonica, n. sp. 
PLATE XXXVI, FIGS. 24-26. 
Capitulum ovate in outline, patelliform; length to greatest width as 5 to 4. 
Surface gently conical, slightly depressed on the posterior slope. The apex 
is truncated by a horizontal plane, forming a relatively large central aperture 
having approximately the outline of the shell itself, and a length equal to 
one-third that of the shell. 
The substance of the shell is apparently thin; its surface marked by 
faint radiating striae or elevated lines. There is no apparent evidence of 
the separate original plates, all having been coalesced into a single external 
