ORAPTOI.ITES OF NEW YOUK. PART 1 721 



Hall's description that they would have to be separated if they were not 

 intermixed with numerous transitional and some typical forms. It is how- 

 ever unmistakable that here a strong tendency to the production of a coarser 

 form is displayed. 



Diplograptus inutilis Hall 



Plato 16, figures 12, 13 



Diplograptus inntilis Hall. Geol. Sur. Can. decade 2. 1865. p.111, pl.l3, 



fig.14 

 Diplograptus inutilis Gurley. .Tour. Gcol. 1896. 4:298 

 Diplograptus inutilis Ruedemann. N. Y. State Paleontol. An. Rep't. 1902. 



p.570 



A few specimens of a diprionid form agree ^vith the incomplete 

 original description and figures of this not very well known species. 



Description. The rhabdosome was pi-obably of moderate size (length 

 of one specimen 7 ram, of the fragment of another 11.4 mm) ; attaining a 

 maximal width of 2 . 4 mm, from which it gradual)}' tapered to the antisiciilar 

 end. The tbecae are curved; number 12 to 10 mm ; are inclined about 40°; 

 in contact for one half of theii' length. Their outer mai-gins are sti'ongly 

 curved, first convex, then concave, abruptly bending outward near the 

 apertures and forming a blunt niucronate extension of the aperture, which 

 extends at right angle to the axis. The aperture is straight or slightly con- 

 vex and also a[)pr()ximately perpendicular to the axis. Virgula very strong. 

 Appendages of sicular end not observed. 



Position and locality. Veiy rare at the Deep kill in the horizon Avith 

 Diplograptus den tat us, to which it is also restricted in Canada 

 I Hall and Gurley]. 



Itemarhs. The specimens here figured agree with Hall's originals in 

 the width of the rhabdosome, the perpendicular position of the free portions 

 of the thecae in regard to the axis, the nunibei- of thecae in a given space 

 and the niucronate prolongations of the apertures. The type specimens were 

 also found in the same association, in the Quebec shales of Point Levis, as those 

 here desciibed. 



