GRAPTOLITES OF NEW YORK, PART 2 iSl 



of the branches measure i mm or nearly that. Longitudinally there are 

 about 6 or 7 meshes in 25 mm. 



Horizon and locality. Devonian (Hamilton formation), Moscow, N. Y. 

 Specimens including the type in the American Museum of Natural History, 

 New York city. 



We may add to Gurley's description that the type specimen while in 

 its major part a typical round meshed Desmograptus shows in its upper part 

 distinct evidence of transition into a Dictyonema s. sir. and may hence be 

 but a fragment of the basal portion of a larger rhabdosome. 



No thecal denticles are visible on the specimen and the component 

 tubes of the branches fail likewise to be observed through the thick 

 smooth perisark of the branches. From Dictyonema hamiltoniae 

 this form is easily distinguished, even if it should be a Dictyonema, by the 

 greater coarseness of its whole structure. Gurley in 1896 proposed a new 

 name for this form on the ground that Hall's name is but a nouicn nudum, 

 but since Hall's type was known no necessity for proposing a new name 

 existed and the retention of the old name in describing the species was 

 quite proper. 



Desmograptus vandelooi sp. nov. 1 



Plate 5, figure 2 



Description. Rhabdosome probably fiabelliforni, consisting of a very 

 irregular and rather fine meshwork, the branches in some parts subparallel 

 with distinct dissepiments, in others undulating and merely re-fusing at the 

 points of contact. The meshes accordingly elliptic to rounded squarish or 

 rectangular. There are 8 to 1 1 branches in 10 mm transversely and about 

 6 to 8 longitudinally. The branches are in the average .6 mm wide and the 

 meshes measure twice as much. The dissepiments where present, are 

 straight and half as wide as the branches. 



The thecae, and the stem have not been observed. 



Formation and locality. One specimen from the Hamilton beds (near 

 their base) of Hemlock creek, Richmond township, Ontario co., N. Y. 



1 Named in honor of the late Christian Van Deloo, who for more than a score of years 

 was one of Professor Hall's most industrious and successful collectors of fossils and also 

 secured the specimen here described. 



