DENDROID GRAPTOLITES OF HAMILTON, ONTARIO. 



59 



This species cau be told by the distiuct and iiumerons "denticles" on both 

 sides of stem and branches, finer and less blnnt dentate than in .1. rjranii. 



Horizon and locality. — Niagaran (Lockport), ITaniilton, Ontario. 

 PU'siotf/pes.^Csit. Xos. 54277, 55317, U.S.N.M. 



Figs. 78-80. — Acaxthograptus walkeri (Spencer). 78, Branches showing buaxch- 



LETS AND thecal APERTURE, X 5 ; 79, A SPECIMEN NATURAL SIZE, ROCHESTER SHALE, 



New York ; 80, Fragment of branch, X 5, Rochester shale. New York. (79 and 



80 are after llUEDEMANN.) 



ACANTHOGRAPTUS PULCHER Spencer. 



Plate 4, figure 5. 

 Acanihograptus pulcher Spencer, Canadian Nat., X, 1SS2, p. 1G5, nomcn 

 nudum; Trans. Acad. Sci. St. Louis, IV, 18S4, pp. 5G4, 582, 588, pi. 4. 

 fig. 6; Bull. Mus. Univ. State Missouri, I, 1SS4, pp. 14, 32, 33. pi. 4, 

 fig. 6.— Miller, North Amer. Geol. and Pal., 1SS9, p. 170, fig. 128.— 

 Gurley, Jouru. Geol., IV, 1896, pp. 92, 308. 



The original description is as follows : 



This frond is broadly flabellate, but was possibly cyathiform in its growing 

 state. Very numerous branches (with few principal subdivisions) arise from 

 a common radicle and extend in an entirely free manner to the even and more 

 or less circular margin of the frond. Along both sides of the branches many 

 short rudimentary branchlets arise. Besides these, there are numerous spine- 

 like processes, which possibly indicate the position of tlie cellules. The texture 

 is corneous, with the surface striated, and in some places, where removed, there 

 are indications of a lateral solid axis. From the center of the radicle the 

 branches extend a distance of about 2i mm. [centimeters. II. R. G.] to the margin 

 of the ground [frond. R. R. G.], or the diameter is about 5 mm. [centimeters. 

 R. It. G.]. The branches are half a millimeter thick. The rudimentary branch- 

 lets, irregularly situated, are seldom more than 2 mm. long, and are stout, while 

 the spinelike processes have a length of half a millimeter, and are about the 

 same distances apart, beftig very slender. 



The branches of this exceedingly beautiful frond (as I have only one complete 

 siiecimen) appear to have occupied a semicircular position when alive, but iu 



