GRAPTOLITES OF NEW YORK. TART 2 



165 



We have added a natural size drawing and a camera enlargement of 

 one of Gurley's three types (cotypes). 



Dictyonema crassum Girty 



Plate 5, figures 3, 4 



Dictyonema crassu m Girty. N. Y. State Geol. 14th An. Rep't, 1894. 1895. p. 289; 

 pi. 4, fig. 1, 2 

 The original description of this species is : 



Shape of entire frond not known. The largest fragment measures 7.5 

 by 7.5 cm. The branches are marked by coarse longitudinal striae, or 

 wrinkles, which are not continuous. The dissepiments are nearly equal in 

 size and parallel in direction, forming with the branches a rather uniform 

 reticulation. Both branches and dissepiments are enlarged at their point 

 of union, giving the fenestrules a more or less rounded 

 form. Thickness of branches, .5 to 1 mm. Dissepiments 

 of about the same size. The specimens examined are 

 casts. 



The zoarium in Dictyonema crassum is 

 coarser than in D. retiforme Hall, of the Niagara 

 group, the dissepiments heavier, and the fenestrules more 

 rounded. 



The quality of the material would hardly warrant the 

 description of a new species, were it not that this is the 

 first appearance of the genus noted in Lower Helderberg 

 strata. 



Horizon. Shaly limestone. 



Locality. Clarksville, Albany co., N. Y. 



Since this careful and correct description is accompanied only by 

 camera enlargements of portions giving the outlines of the fenestrules and 

 therefore furnishing a very inadequate picture for purposes of comparison, 

 I have inserted here an enlargement and a natural size drawing of a portion 

 of the type specimen which was kindly loaned to me by Professor Schuchert. 



Better preserved than the two type specimens which were collected by 

 the late Professor Beecher in the Helderbergs near Albany and are now in 

 the Yale University Museum, are numerous specimens now in the New 

 York State Museum. One of these, still further to be noted below is 

 from the New Scotland limestone (Shaly limestone) near Catskill, N. Y. 

 and the remainder are from the same formation in the Jonesburg quarry q.t 



Fig. 74 Dictyonema 

 c rass u m Girty. Enlarge- 

 ment (x 5) of portion of type 

 specimen 



