PALEONTOLOGIC CONTRIBUTIONS 



21 



It is therefore for the present a fair conclusion that the horizon 

 bearing the Dictyonema furciferii m corresponds roughly 

 to the Fort Cassin beds which are in D of the New York Beekman- 

 town section. 



The writer had recorded the occurrence of D. furciferum 

 from graptolite bed 2 (Tetragraptus zone) and bed 3 (lowest of 

 zone with Didymograptus bifid us). The type specimen 

 is from the former, where on the same 

 slab the common forms of that zone, 

 together with a type of Tetra- 

 graptus fruticosus are seen. 

 The specimens from the following 

 zone are very fragmentary and not so 

 safe for a correlation. The inference 

 would thus be proper that the upper 

 part of the Tetragraptus horizon and 

 possibly the lower one of the Didy- 

 mograptus-bifidus horizon, may ap- 

 proximately correspond in age to the 

 Fort Cassin beds or the upper part of 

 D CD,).* 



Fig. 9 C 1 i m a c o g r a p - 

 tus parvus Hall. Synrhab- 

 dosome, or entire colonial 

 stock. Natural size 



Climacograptus parvus Hall 



The writer has before 2 described entire colonial stocks (syn- 

 rhabdosomes) of the genera Diplograptus (D. incisus, 

 euglyphus var. pygmaeus), Glossograptus (G. 

 q u ad rimucronatus and varieties) and Lasiograptus 

 (L. eucharis and mucronatus). It was shown 3 that 



1 Since this note was written, the Bibliographic Index of American Ordo- 

 vician and Silurian Fossils- by Dr Ray S. Bassler has been published, and 

 in this welcome publication Dictyonema furciferum is placed into 

 the base of the Stonehenge at Bellefonte, Pa., as Doctor Bassler writes me, 

 on information furnished by Doctor Ulrich. This would make the horizon 

 with Tetragraptus as old as the Tribes Hill limestone or the base of the 

 Beekmantown (part of division B, A, now being correlated with the Little 

 Falls dolomite, which is Ozarkian in age). On the other hand, Doctor Ray- 

 mond has meanwhile (in The Succession of Faunas at Levis, P. Q., in Amer. 

 Jour. Science, v. 38, 1914, p. 529) recorded the same species from the horizon 

 with Diplograptus dentatus at Quebec. This identification, if 

 correct, would give the species such a long range as to make it useless for 

 purposes of correlation. 



2 N. Y. State Mus. Mem. 11, pt 2. 1908. 



3 R. Ruedemann. Annual Rep't N. Y. State Geol. 1894, p. 219 f. 



