GRAPXOLITES OF NEW YOKK, PAUT 1 521 



such forms, collected by the writer some years ago in the Normanskill shale 

 of Mt Moreno, as well as an inspection of Hall's types in the American 

 Museum of Natural History, have convinced us that these apparent 

 appendages are of the character of the peripheral fibrous tissues of 

 Lasiograptus, as will be more fully shown in the second memoir on the 

 Graptolites of New York Freeh [1897, p.551] has suggested that these 

 appendages may have been " Deckstiicke " (protective persons) or swimming 

 bells (nectophores). 



Nicholson saw gonaugia in elliptic or orbicular chitinous bodies, for 

 .which he proposed the name Dawsoniae. These very common bodies have 

 however never been found attached to graptolite rhabdosomes and form 

 probably themselves an aberrant type of graptolites [Appendix, p.738]. 



Holm and Wiman have recognized the presence of small tubes in the 

 Dendroidea which ilank the thecae, and asserted the gonangial function of 

 these. No sicula has been found in connection with these tubes, while 

 distinct siculae occur in the Dendroidea, as for instance in Dictyonema 

 flabelliforme [pl.l]. Freeh considers these tubes homologous to the 

 nematophores of the living Plumularidae. 



Cysts, actually containing siculae, of two species of Diplograptus, 

 have been described by the writer [1897]. [^See text fig.9]. These 

 were held to be gonangia or organs for sexual propagation. Wiman has 

 expressed his dissenting belief that they ought rather to be considered 

 individuals of asexual propagation or budding individuals [1895, p.73 ; 

 1896, p.l92]. In support of my own conception I would cite the following 

 arguments : 



1 The homology in the structure and development of the sicula and 

 the embryos of Hydroidea, as Eudendrium, which is discussed below 

 [p.523]. The embryos of Eudendrium are, of course, of sexual origin. 



2 Every rhabdosome begins its growth with a sicula. As new colonies 

 among the recent Cnidaria and other colony-forming invertebrates take, with 

 rare exception, their inception from sexually produced embryos, it is to be 

 inferred that these extinct rhabdosomes also originated from such. It is 



