68 NEW YORK STATE MUSEUM 



arate names, as an attempt to do so in the case of the goniatites has 

 shown, but it would be perfectly possible to name each racial line by 

 its terminal member, as line i of our diagram that of D i d y m o - 

 graptus forcipifer, and retain for practical reasons the 

 polyphyletic " genera " Tetragraptus etc. with the understanding 

 that they are not true genera. The writer has proposed (in Memoir 

 7, 1904) to term them " Geologic genera," while Gregory's better 

 term " circulus " has come into use for these groups of homoeo- 

 morphs. 



Similar conditions seem to prevail also among the axonophorous 

 graptolites where the genera Diplograptus, Climacograptus and 

 Monograptus apparently fall into racial lines. 



We have then here the same phenomenon of polyphyletic develop- 

 ment of " genera " so well known from the ammonites and brachi- 

 opods through the investigations of Buckman and others, and also 

 recognized among the vertebrates, as in the case of the development 

 of the horses in America and Europe. 



Bibliography 

 Hall, Geological Survey of Canada. Figures and Descriptions of Canadian 



Organic Remains, decade 2, 1865 

 Nicholson, H. A. & Marr, J. E. Phylogcny of the Graptolites. Geol. Mag. 



dec. 4, V. 2, 1895 

 Elles, G. L. Graptolite Fauna of the Skiddaw Slates. Quar. Jour. Geol. 



Soc. 54: 529, 1898 

 Hall, T. S. Reports on Graptolites. Reo. Geol. Surv. Australia v. I. 1906. 



p. 266 

 Elles, G. L. & Wood, E. M. R. Monograph of British Graptolites; ed, by 



C . Lapworth 

 Ruedemann, R. Graptolites of New York, pt i, p. 553. 1904 

 Grabau, A. W. Principles of Stratigraphy, New York, 1913. 



2 On Sex Distinction in Fossil Cephalopods 



The upper Utica shale at Holland Patent contains in close asso- 

 ciation in the same bed, three different forms of breviconic cephal- 

 opods, namely, a larger and a smaller form with contracted apertures 

 and a smaller form with open aperture. According to the usual 

 procedure, these would be distinguished as different species ; the first 

 two as belonging to Oncoceras, the third as a Cyrtoceras. 



The fact that both the larger and smaller forms with contracted 

 apertures exhibit more closely arranged septa just below the living 

 chamber, indicates that the contracted aperture actually indicates a 

 gerontic condition and that both forms, the larger and smaller, had 

 reached or passed maturity. Outside of this difiference in size, the 

 two forms asree absolutelv in all other characters, as relative rate of 



