NORTH AMERICAN GRAPTOLITES 83 
oblique. Meshes correspondingly variable in shape, from quadrangular to 
triangular. The shortest are about 1.25™™" long, and the greatest length in 
unbroken meshes (¢. ¢., where all the dissepiments are entire) is probably near 
3™". Texture Carbonaceous. Branches rather obscurely striate, dividing 
at an acute, rather sharp, angle. 
Resembles somewhat 2. gvacz/e Hall, but the branches are a little more 
slender and the interspaces a little wider, and especially the number of 
branches transversely in this species is less (20-25 as against 25—30 in D. 
gracile), | am indebted to Mr. Charles Schuchert for having drawn my 
attention to this species. 
Horizon and locality—Lower Carboniferous (Choteau limestone), Sedalia, 
Mo. Collected by and dedicated to Mr. R. A. Blair, of Sedalia. 
DESMOGRAPTUS HOPKINSON, 1875. 
Quar. Jour. Geol. Soc., London, XXXI1., p. 668. Type, D. cancellatum Hopk. 
Desmograptus macrodictyum Gurley, sp. nov. 
Polypary subparallel, rather abruptly widening from a non-siculate, 
fibrous, root-like base; branches thick, almost straight, longitudinally striate, 
bifurcating quite regularly ; bifurcations evenly rounded, the dividing branches 
curving into parallelism and coalescing prior to redivision. Thecal mouths 
pressed against the stem, appearing as rounded or transversely oval eleva- 
tions, about 36 in 25™. Meshes very long in proportion to-their width, 
formed only by the coalescence of the branches, true dissepiments being 
entirely absent. 
Horizon and locality.—Calciferous shales, Point Levis, Canada. 
This species differs decidely from all species of Dzéctyomema except 
D. cancellatum Hopk., for which its author proposed (as a subgenus) Desmo- 
graptus, saying : 
“The most distinctive characteristic is that the meshes or interspaces are 
chiefly formed by the branches coalescing and dividing by virtue of their 
curvilinear direction, being connected by transverse filaments only here and 
there where not sufficiently undulated to be brought quite into contact, and 
not being connected at all where the undulations do not bring the branches 
into tolerably close proximity to each other.”’ 
In the species here described no dissepiments are anywhere visible, the 
division of branches appearing to take place mostly at regular intervals, a 
series of divisions extending across the whole width of the polypary at the 
same level. I regard Desmograptus as entitled to full generic rank if, as I 
think, D macrodictyum belongs to it. 
From all species it is distinguished by the entire absence of dissepiments ; 
from D. cancel/latum in particular by the straight branches, the greatly elon- 
gated meshes and the generally stouter structure. 
