NORTH AMERICAN GRAPTOLITES 69 
at end of first theca to 240°; branches continued in a gentle, flexuous curve 
to their extremities, averaging in width about 0.5. Thecz 30 or 32 in 25™™; 
adnate to the coenosarcal canal, with straight or very slightly convex margins 
and slightly inclined apertural edge. 
The affinities of this form are distinctly with S. fertenuzs Lapworth and its 
associates, S. exflanatus and S. nttidulus. From all these, however, it differs 
in absence of secondary branches and in general form of polypary. 
Horizon and locality.—Lower Dicellograpsus zone, Stockport, N Y. 
To the above description I may add that some specimens indicate that 
the primary branches give origin to secondary ones, probably from the athe- 
caphorous margin. 
AZYGOGRAPTUS NICHOLSON, 1875. 
Ann. and Mag. Nat. Hist., XVI., p. 269. Type, A. dapwortht Nich. 
Azygograptus? walcotti Lapworth, sp. nov. 
Polypary unilateral, monoprionidian, consisting of a single flexuous and 
simple compressed branch proceeding almost horizontally from the side of an 
inconspicuous sicula, 50 to 75™™ in length, in average diameter about 0.5™™. 
Thecz 16 in 25™™, without overlap, consisting of conical tubes, increasing 
slightly in diameter throughout, adnate to the coenosarcal canal, with straight 
or slightly convex ventral margins. Apertural margin a little inclined and 
projecting from the ventral margin for a distance equal to about one-half the 
diameter of the polypary and transgressing upon the periderm for a similar 
distance. Denticle almost rectangular; excavations and interspaces shallow 
and inconspicuous. 
Horizon and locality.—Lower Dzcellograpsus zone, Stockport, N. Y. 
This form has all the appearance of belonging to the curious genus 
Azygograptus. "Two specimens occur in the collection. One lacks the prox- 
imal part; in the other there is evidence of the unilateral nature of the 
polypary and of the presence of the sicula. Further research may show that 
it belongs to the bilateral genus Leffograptis, but in any case it is a new and 
undescribed form of the family. If it actually belong to Azygograptus, this 
is the first specimen of the genus on the American side of the Atlantic, and 
there is special appropriateness in its dedication to Mr. Walcott, whose recent 
researches have done so much to elucidate the sequence and fossils of the 
strata in which it occurs. 
LEPTOGRAPTUS LAPWORTH, 1873. 
Geol. Mag. London, X, p. 558. Type, Z. flaccidus (Hall). 
Leptograptus ? macrotheca Gurley, sp. nov. 
Known only in the form of a fragment of a branch. Thecz long, curved, 
slender, finally becoming nearly perpendicular to the branch but slightly 
