GRAPTOLITES OF NEW YORK, PART 2 443 



described by me in Memoir 7 as Di plograptus I ax us sp. nov. and 

 Cryptograptus an ten 11a ri us (Hall) are but two aspects of one 

 (the latter) species, one ot which alone had been described and figured 

 by Hall. A renewed investigation of the respective Deepkill material has 

 brought out the fact that the specimen reproduced on plate 16, figure 26, 

 op. cit. presents both aspects in its upper and lower parts. An enlarged 

 drawing of this specimen is here inserted [text fig. 418.] 



It is interesting to note in this connection that the same two aspects of 

 C. antennarius occur in the Beekmantown shales of Arkansas and 

 that Dr Guide)', as an inspection of his material and labels has shown to 

 the writer, has identified the frontal aspect with C . ante n n a r i u s, the 

 lateral aspect, however, with C. tricornis, and consequently cites both 

 species as being associated in these shales [ 1890, p. 415 ; 1896, p. 299.] 



If Diplograptus laxus is united with C . ante 11 n a r i u s as a 

 synonym, both American representatives of the genus show such close simi- 

 larity of their characters that their phylogenetic connection can be hardly 

 gainsaid. The form and closeness of arrangement of the thecae are the same 

 and only the dimensions of the rhabdosomes and of the apertural spines 

 are different. The inflation of the nemacaulus had already been acquired 

 in the Deepkill form and is shown in several specimens of "Diplograp- 

 tus 1 a x u s." 



Cryptograptus tricornis (Carruthers) 



Plate 28, figures 1-4 



Diplograptus tricornis Carruthers. Roy. Phys. Soc. Trans. Edinburgh. 



1858. 1 1468, fig. 2 

 Diplograptus tricornis Carruthers. Ann. & Mag. Nat. Hist. 185Q. 3 125, 



fig. 2 

 Graptolithus marcidus Hall. Pal. N. Y. 1859. 3:515, fig. 1-3 

 Graptolithus marcidus Hall. N. Y. State Cab. Nat. Hist. 13th An. Rep't. 



i860, p. 58, 59, fig. 1-3 

 Diplograptus tricornis Carruthers. Geol. Mag. 1868. 5:131, t. 5, fig. 1 1 

 Diplograptus etheridgii Hopkinson. Geol. Mag. 1872. 9:504, t. 12, fig. 5 

 Diplograptus tricornis Hopkinson & Lapworth. Geol. Soc. Ouar. Jour. 



1875- 3 i:6 5 8 > t- 35. fi g- f) 



