tOWER SILU'RIC shales OF THE MOHAWK VALLEY 75 



fossils and their -character of flotation appendages. We are not 

 sure yet to which of the two species here distinguished they belong, 

 although the present evidence indicates that they are referable to 

 S.latifolius. 



Several specimens of S. latifolius appear at first glance 

 lobate (see plate i, figure i). It has been pointed out to me by 

 Mr White that this appearance is due to the presence of cuplike 

 marginal cavities and that these are apparently connected with the 

 neural system which is canalicular. These ciips and the canals are 

 well seen in plate i, figure 2. 



Besides the genotype, S. latifolius, which according to 

 the original description possesses " broadly cuneate thalli,^ " we 

 have distinguished a second species, but there are probably more 

 than two species present, as indicated by such thalli as those repro- 

 duced in plate i, figure 9. The cuneate thalli ofS. latifolius 

 were probably arranged spirally around a stem, as indicated by their 

 wedgelike shape and by the specimen plate i, figure 13. 



The largest thalli found are those' typically represented by plate 

 I, figure 5. While also possessing a broadly cuneate to trap- 

 ezoidal outline, they are not single as those of S. latifolius, 

 but, as again pointed out to us by Mr White, " composed of rather 

 slender, but rigid conical thalli, originating at the scarlike pits or 

 depressions of the lower parts of the axis." 



A third (type is represented by plate i, figure 9. Only one speci- 

 men of this interesting form has been thus far obtained. It shows 

 a pitted middle axis from which proceed lobate thalli, ornamented 

 with broadly recurving lines. This material we consider too im- 

 perfect for specific differentiation. 



Cyathodictya ? tubularis no v. 



r Certain layers of the Canajoharie beds at Canajoharie are 

 ■:overed with multitudes of small elongate bodies which contrast by 

 their brown coloring with the black shale. These bodies are mostly 

 ■ibout 5 mm long and then regularly conical in outline, but reach as 



1 



I 1 The original description is : " Leaves broadly cuneate, somewhat 

 thickened at the outer margin, and truncate at the lower extremity; 

 surface obscurely striated. The specimens are often marked on one side 

 by a ridge or midrib along the center, and sometimes transversely wrin- 

 kled. These leaves all appear to have been thick and succulent, like the 

 Fuci." 



