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NEW YORK STATE MUSEUM 



transversely elliptic slightly projecting apertures surrounded by a 

 thickened rim and appear to alternate on opposite sides of the stem 

 and branches. 



There are no traces of internal walls observable in the badly 

 flattened specimens. 



While it is perfectly conceivable that all the apparent apertures 

 could be but the former places of attachment of lost branches, it 

 is also quite as sure that this form, found in another association, 

 would be unhesitatingly referred to the graptolites and brought 

 into the neighborhood of Mastigograptus where it closely resembles 

 in general habit and structure the Utica form, M . arundi- 

 naceus (Hall). 



As in the case of Corematocladus densa the car- 

 bonaceous test is so thick and so glossy that it is more suggestive 

 of the chitinous periderm of a graptolite than of the cortex of an 

 alga and it would require unmistakable algal characters in the 

 composition of the branches and the propagative organs to war- 

 rant a reference to the vegetable kingdom. 



Horizon and locality. In the shaly intercalation of the lowest 

 limestone beds overlying the " Black marble " at Glens Falls, 

 N. Y. 



Concluding Remarks 



There are in this paper more fully noted three species of fossils 

 from the Trenton rocks of New York whose position among the 

 marine algae seems fairly well established. These are : 



Primicorallina trentonensis Whitfield Callithamnopsis delicatula sp. nov. 

 Corematocladus densa sp. nov. 



The first named is a calcareous alga, which before was placed 

 among the Coralline algae, but is believed by the writer to be a 

 verticillate Siphonea. The other two forms possess only car- 

 bonaceous tests and are characterized by the great mass of thin 

 branchlets borne on the axial stem. In Callithamnopsis 

 delicatula these branchlets are arranged in whorls, in the 

 other form they are irregularly distributed on the thick axial 

 stem and frequently bifurcate. The aspect of these forms is that 

 of Florideae and their habitus, which alone is now available, per- 

 mits of comparison with several families of that class. 



It is probable that calcareous algae have played an important 

 role in the formation of the limestones of the Trenton formation. 

 This is not only suggested by the frequency of the small joints of 

 Primicorallina in the rock which contains the types, but also by 

 the fact that there occur peculiarly granular and oolitic lime- 



