DENDROID GRAPTOLITES OF HAMILTON, ONTARIO. 



27 



Ruedemann. Spencer's original description, with additions from his 

 description of 1884 contained in brackets, is given below : 



Frond circular, but cynthiform in its growing state. There are numerous 

 bifurcating branches, which in the fossil condition imperfectly unite or overlie 

 each other, producing a kind of flue network with irregular sub-rhomboidal 

 [ellipsoidal] interstices. In texture it is corneous, having the branches marked 

 with striations of a sub-rhomboidal form. 



In this species the branches are much finer (but little more than one-eightieth 

 of an inch in width [0.35-0.75 mm.] ) than in C*. cyathiformis, with more numerous 

 aod irregular bifurcations, producing a netted appearance. The original matter 

 is often replaced by pyrites. The fronds are not generally more than two inches 



VUiS. oO, 31. DlCTYONEMA SDBRETIFORME (SPEXCER). 30, One OF SpEXCER's TYPES OE 



Calyptograptds subretiformis. (After Spencer.) 31, A large expanded rhabdo- 



.SOMB FROM THE ROCHESTER SHALES OF NEW YORK. (COPIED FROM RUEDEMANN.) 



in diameter. Only a few si)ecimens have been found, and these show some 

 varietal differences. 



This species was found in the Niagara limestone [principally in the shaly dolo- 

 mites beneath the chert bed], Hamilton, Ontario, by Colonel Grant. 



To this description (hirley adds the following: 



Measurements of a number of branches show that these nearly all fall between 

 0.4 mm. and O.G mm., 0.4-0.5 being the dimensions usual in the distal portion for 

 the branches exclusive of the terminal twigs. The more proximal stems meas- 

 ure 0.6 mm., and the thickest seen (in one specimen only) reached 0.8 nun. Cor- 

 responding to the straggling aspect of this species almost any number of branches 

 may be counted transversely, but if portions be selected where the branches are 



