GRAPTOLITES OF NEW YORK, PART 2 



26l 



Leptograptus flaccidus (Hall) mut. trentonensis nov. 



Plate 14, figures 6, 7 



Description. Rhabdosome attaining great length (branches of 27+ cm 

 not rare) ; branches slender and flexed, first convex, then gently concave or 

 mostly straight and horizontal, frequently drifted into thick bundles of 

 parallel branches [fig. 7 part of one]; diverging in the proximal region at 

 an angle of 220°-240°, having an initial width of .4 mm, and increasing 

 gradually to a width of 1 mm, which is then maintained. The sicula meas- 

 ures 1.5 mm. It often bears a long (.8 mm) needlelike, apertural spine 



174 



Fig. 172-75 Leptograptus flaccidus mut. trentonensis nov._ Fig. 172 

 Obverse view showing long virgella. Fig. 173, 174 Reverse views of the sicular end. 

 Fig. 175 Copies of Lapworth's (manuscript) enlargements of L. subtenuis from 

 Stockport, N. Y. [see p. 255]. Figures 172-74, x 5 ; figure 175, x 8 



175 



(virgella). The first theca originates in the apertural half of the sicula and 

 the next close to the budding point of the first. The four primary thecae 

 diverge horizontally from the apertural part of the sicula. They are fur- 

 nished with distinct mucros. The thecae are narrow and long, number 7 

 to 10 in 10 mm (the variations in the proximal portions of the branches 

 amounting to 8 to 10 in different specimens and those in the distal parts to 

 7 to 8), and overlap in the proximal portion of the branches about one third 

 their length, in the mature portion one half. They exhibit when seen in 

 profile a small angle of inclination (15°) and a normally straight or slightly 

 concave aperture that is slightly introverted and opens within a shallow 

 short excavation. 



