GRAPTOLITES OF NEW YORK, PART 2 247 



MEGALOGRAPTUS Miller 



The genus Megalograptus has been erected by Miller [Cin. Ouar. 

 Jour. 1874, 1 : .343.1 for a supposed graptolite, characterized by very large, 

 cylindrical fronds with spinose processes and covered with cellular open- 

 ings. The type is M . welch i, occurring" in the Richmond beds of 

 Cincinnati. Dr Ulrich informs me that the types of this form are fragments 

 of a crustacean that is identical or closely related to E c h i n o g n a t h u s 

 clevelandi Walcott and Professor Foerste has lately shown me a draw- 

 ing — to be published in his forthcoming work on the Richmond fauna — 

 of an excellently preserved specimen that clearly exhibits its crustacean 

 nature. 



Order n GRAPTOLOIDEA Lapworth 



Suborder A graptoloidea axonolipa Freeh em. Ruedemann 



Family dichograptidae Lapworth 



DIDYMOGRAPTUS McCoy 



The morphology and phylogeny of Didymograptus have been fully 

 noted in Memoir 7, since this group of forms not only clearly attains its 

 full development but also proceeds far on the road to extinction in our 

 lower graptolite beds. While we recorded 17 species from the latter, we 

 find only 3 species left in the lowest zone of the upper beds and in the 

 Utica shale Didymograptus has disappeared entirely. Of these three 

 species two, viz: D. sagitticaulis and D . serratulus belong to 

 the group with declined branches, and one, D. subtenuis has nearly 

 horizontal or slightly reclined branches. None of them shows any indica- 

 tions of the rapidly approaching disappearance of this stage in the life 

 history of the Dichograptidae, and two of them are even robust forms with 

 very long branches and of very frequent occurrence in the Trenton shales. 



Didymograptus sagitticaulis Gurley 



Plate 14, figure 3 



Grap toli thus Sagittarius (Hisinger) Hall'. Pal. N. Y. 1847. 1: 272; pi. 74, fig. 1 

 Graptoli thus Sagittarius Walcott. Alb. Inst. Trans. v. 10. 1883. (1879, 

 advance sheet, p. 34) 



