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NEW YORK STATE MUSEUM 



branchlets are liable to form so dense a mass that they completely 

 envelop the main branch. No fructification has been observed. 



This alga probably possessed a very delicate and minute thallus, 

 the largest fragments not attaining 20 mm in length. The car- 

 bonaceous test of the branches is much thinner than in the genotype 

 and also than that of the associated algae in the Trenton limestone 

 at Glens Falls and only visible with good light. 



From the genotype it is distinguished by the generally greater 

 tenderness of the whole thallus, that finds its expression in the 

 thinner main branch and thinner and more flaccid branchlets and 

 also in the closer arrangement of the whorls on the main stipe. 

 The contraction of the latter between the annuli produced by the 

 bases of the whorled branchlets constitutes another difference. 



Horizon and locality. In the Trenton limestone at Glens Falls, 

 N. Y. 



Chaetocladus Whitfield 

 For a new species of supposed algae from Platteville, Wis., Pro- 

 fessor Whitfield has proposed the genus Chaetocladus, character- 

 izing the same as consisting of " Marine plants with jointed cylin- 

 drical stems giving off whorls of hairlike filaments at given dis- 

 tances." 



Chaetocladus plum u la Whitfield 

 Fig. 11 Type specimen, X3 



Fig. 12, 13 Further enlargements. (Copies from Whitfield) 



We insert the original drawings [see text fig. 11—13] °f tms P e ~ 

 culiar form for comparison with <the form here referred to that 

 genus. It will be seen from the second figure that the branchlets 

 may bifurcate again. 



Chaetocladus sardesoni sp. nov. 



Plate 2, figures 3-1 1 



Professor Sardeson sent me some years ago a piece of magnesian 

 limestone from the Bellerophon bed (Trenton-Galena bed 2 of his 



