70 R. R. GURLEY 
inclined distalwards; apertural margin straight ; proximal margin concave, 
not uniformly, but with a bluntly rounded angle. Thecz 16-17 in 25™™. 
Branch including theczee 1™™ wide, of which the coenosarcal canal occupies 
about two-sevenths. 
Horizon and locality.—Calciferous shales, Point Levis, Canada. 
DICELLOGRAPSUS HOPKINSON, 1871. 
Geol. Mag., VIII., p. 20. Type, D. elegans (Carruthers). 
Dicellograpsus intortus* polythecatus Gurley, var nov. 
A species occurs at Stockport which presents a close resemblance to Lap- 
worth’s species but shows some important differences, at least from his pub- 
lished description and figures. These differences are sufficient to justify its 
provisional varietal separation, although it is possible that they may be due 
to the structure being more perfectly shown by the Stockport specimens. It 
resembles Lapworth’s species, in the mode of growth, character of thecee and 
dimensions of the branches. Like that species the present form is alsoa 
Norman’s Kill (=Glenkiln) form. The thecee are uniformly 32 in 25™™. 
The first six or eight bear spines almost as long as the thece. But the most 
important difference is that the mode of growth is exactly the same as that 
exemplified by Dicranograptus furcatus (Hall), that is to say, the thece are 
present alternately on the outer and inner margins of the branches, and the 
latter cross alternately over and under, showing a growth in opposite-turning 
spirals. Lapworth’s figures indeed not only do not show this feature but on 
the contrary show the opposite condition. Nevertheless the conformity of 
type is so close that I suspect that this omission is an error, and that the 
British form, as well as the American, has the spiral mode of growth. 
Where the proximal portion of the polypary is absent the appearance may 
resemble somewhat that of Dicranograptus furcatus (Hall) under similar con- 
ditions. The latter species has, however, much thicker branches (1™™ as against 
0.6™™ for the present form), the thecae are much coarser and are a// provided 
with strong spines. The loops are also more elongate and narrow. 
Horizon and locality._Lower Diécellograpsus zone, Stockport, N. Y. 
Dicellograpsus gurleyt Lapworth, sp. nov. 
Branches from 25™™ to roo™™ long, slender, gently concave distally; diverg- 
ing immediately from sicula at an angle of 270°, which slowly decreases to 
a general angle of 240°; width at origin about 0.5"; maximum diameter 
1.25™™ in adult parts of polypary. Thecz averaging about 24 to 26 in 25™™. 
without overlap, compressed proximally to form a deep excavation ; ventral 
margin straight for first three-fourths of its length; convex in last fourth, 
Distal portion of theca of the rounded type found in the genus, isolated and 
t Dicellograpsus intortus Lapworth, was described in Ann. and Mag. Nat. Hist. 
1880, V., p. 161, Plate XIX., Figs. 19 a-c. 
