2l6 NEW YORK STATE MUSEUM 



incomplete knowledge of their structure. Such genera are Thamnograptus 

 Hall, Phycograptus Gurley and Strophograptus Ruedemann. The genus 

 Thamnograptus has by means of some excellently preserved specimens been 

 found not to differ materially from other graptolites, in the composition of its 

 branches of thecae which successively bud in single series [.swpl.9, fig. 13]. 

 Phycograptus is described by its author as distinctly segmented, but as 

 shown by the present writer [see p. 245] probably based, in part at least, on 

 infrequent states of preservation of other forms, hence very doubtful in its 

 validity and character. Strophograptus finally has been erected [ 1904, 

 p. 716] for long capilliform, unbranched pitted fibers found in dense bundles 

 in the older graptolite rocks. It is possible that these masses of long, 

 parallel threads are the drifted remains of a Mastigograptus with exceed- 

 ingly long, undivided, terminal branches ; but as long as entire rhabdosomes 

 have not been observed, a separation of the forms is the safer course. 



Mastigograptus tenuiramosus (Walcott) 



Plate 9, figures 2, 3; plate io, figure 1; plate n, figures 1-4; plate 12, figures 1, 2 



Dendrograptus tenuiramosus Walcott. Utica Slate and Related Formations. 



1879. P- 21 



Dendrograptus tenuiramosus Ulrich. Cat. Foss. Cincinnati Group. 1S80. 



Dendrograptus tenuiramosus Walcott. Alb. Inst. Trans. 1881. 10:21; pi. I, 



fig- 4 

 Dendrograptus tenuiramosus James. Cin. Soc. Nat. Hist. Man. Pal. Cincinnati 



Group, pt 2. 1892 

 Dendrograptus tenuiramosus Harper &: Bassler. Cat. Foss. Trenton & Cin- 

 cinnati Period. 1896. p. 2 

 Dendrograptus tenuiramosus Gurley. Jour. Geol. 1896. 4:300 

 Dendrograptus tenuiramosus Nickles. Cin. Soc. Nat. Hist. Jour. 1902. 20:70 



Description. Rhabdosome forming a densely branched bush attaining 

 a size of 20+ cm ; the branches extremely slender, especially in their long 

 distal portions (.3 mm average width), given off monopodially and alternat- 

 ingly at small, somewhat irregular intervals ( 1.5 mm at an average) and at 

 an angle of 50"; this rather large angle giving the bushes a characteristic 

 shrubby appearance in the central parts [see pi. 9, fig. 2], while the distal 



