GRAPTOLITES OF NEW YORK, PART 2 21 5 



The other alternative that the appendages were gonothecae is opposed 

 by the presence of smaller paired cones on their bases; for these could be 

 readily compared in form and position to the nematocalyces of the recent 

 hydrozoans but would not be represented by analogous structures on the 

 gonangia ; and the regular and close arrangement of the appendages would 

 seem to correspond altogether more to that of thecae than of gonothecae. 

 But since we have seen above that the assumption of the function of these 

 cones as thecae has as a corollary that of the function of the entire rhabdo- 

 some as a hydrocaulus, and all indications point on the contrary to the 

 composition of the rhabdosome of tubular thecae it seems dangerous to 

 press the analogy of the form with the recent hydrozoans too closely and 

 give the general appearance and arrangement of the appendages too much 

 weight. It would also seem that the extremely loose fixation of the conical 

 bodies, indicated by their more frequent detached occurrence and the very 

 rare observation of rhabdosomes bearing them, is more suggestive of their 

 functional connection with the generative process than with any other. 



While at present only one species, the genotype of the proposed 

 genus, is known to bear the free, detachable thecae, other species, as the 

 associated Dendrograptus simplex, possess identical smooth, 

 flexible branches without indications of thecae and no doubt bore like 

 appendages on them when complete. 



To the genus Mastigograptus, as defined by the character of its geno- 

 type, can be safely referred Dendrograptus simplex Walcott and 

 D. gracillimus (Lesq.) since both possess like smooth capilliform 

 branches with rows of pits and occur in the same beds. There is also 

 little doubt that numerous other species now referred to Dendrograptus, 

 as D. serpens Hopk. and some of the older equally slender forms 

 described by Hall from the Quebec region in which but slight indentations 

 were observed as indications of thecae, belong here. 



The relations of the genus Mastigograptus to several other genera 

 also based on forms with capillifOi n or at least very slender branches with 

 pits for "thecal apertures" are still obscure, mainly on account of our 



