FIFTH REPORT OF THE DIRECTOR I908 



209 



stones in the Mohawkian stages (not only in the Trenton and 

 Black River limestone, but also in the Lowville limestone) which 

 may be strongly suspected to be of vegetable origin. In Europe 

 similar rocks of the Lower Siluric have been recognized by Stolley 

 to owe their origin to verticillate Siphoneae. There is neither any 

 doubt that forms corresponding to the important rock-forming 

 nullipores of later eras have been very active then and productive 

 of much of our Lower Siluric limestones, at least in Chazy to 

 Trenton times. This is I ) indicated by the common occurrence* in 

 some of our Mohawkian rocks of Solenopora com pacta, 

 a form that is placed among the calcareous algae by Rothpletz 

 and considered as either an ancestor of the Coralline algae or as 

 representing an earlier development of a corresponding or parallel 

 branch of the algae, and 2) it is demonstrated by the composition 

 of whole beds of all three divisions of our Chazy by the small 

 nodular bodies described by Seely 1 as a new type of sponge under 

 the name of Strephochetus with a small number of species. 

 Professor Seely's careful figures of microscopic sections, especially 

 of his S. ocellatus, leave, however, no doubt that Strepho- 

 chetus is identical with Girvanella N. & E. The latter had already 

 been suspected by Nicholson and Etheridge, and later has been 

 proved by Rothpletz to be a calcareous alga, that invites compari- 

 son with the Siphonean family Codiaceae. If Girvanella is an alga, 

 much of our Chazy limestone is of vegetable origin. 



Also our Eeekmantown beds contain strata filled with similar 

 small flat pebbles that are highly suggestive of the water biscuits 

 of our lakes. 2 For these, occurring frequently in upper D. in the 

 so called " Wing conglomerate of Vermont," Seeley has erected 

 the genus Wingia, 3 considering them again as sponges. It is an 

 inviting task to investigate these and other forms of pebbles of the 

 Beekmantown and late Paleozoic stages as to their possible vege- 

 table origin. 



1 Seely, H. M. Some Sponges of the Chazy Formation. Vt. State Geol. 

 Rep't 1902. p. 151. 



2 Calcareous water biscuit have been described from Canandaigua lake 

 where they largely contribute to the composition of the beach, by Clarke 

 [N. Y. State Mus. Bui. 39. 1900. p. 195]. They are glomerated masses of 

 algae such as are known from many European lakes (''algoid lake balls") 

 that by their own metabolic processes have caused a deposition of carbonate 

 of lime on them. The similarity of the structure of these water balls to that 

 of Girvanella has induced Seward [Fossil Plants, 1895. 1 : 125] to place 

 the latter genus among the Schizophyatc, a view opposed by Rothpletz 

 Hoc. ext. p. 5]. 



3 Seely, H. M. Contribution to the Geology and Paleontology of Vermont. 

 Vt. State Geol. 5th Rep't 1906. p. 25. 



