GRAPTOLrTES OF XEW YORK, TART I 721 



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

 intennixed 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 



Plate 16, figures 12, 13 



Diplograptus inutilis Hall. Geol. Sur. Can. decade 2. 1865. p. Ill, pl.l3, 



iig.14 

 Diplograptus inutilis Gurley. Jour. Geol. 1896. 4:298 

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



p.570 



A few specimens of a diprionid form agree with the incomplete 

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



Description,. The rhabdosome was probal^ly of moderate size (length 

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

 maximal width of 2.4mm, from Avhich it gradually tapered to the antisicular 

 end. The thecae are curved; number 12 to 10 mm; are inclined about 40^; 

 in contact for one half of their length. Their outer margins are strongly 

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

 apertures and forming a blunt miicronate extension of the aperture, Avhich 

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

 vex and also approximately perpendicular to the axis. Virgula very strong. 

 Appendages of sicular end not observed. 



Position and locality. Very rare at the Deep kill in the horizon \\\\\\' 

 Diplograptus dentatus, to which it is also restricted in Canada 

 I Hall and Gurley]. 



Remarlx. 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 j-egard to the axis, the number of thecae in a given space 

 and the mucronate prolongations of the apertures. The tA^pe specimens were 

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

 here described. 



