300 NEW YORK STATE MUSEUM 



smaller angle (240 only in this specimen). This form may be distin- 

 guished as D . divaricatus var. rectus. It occurs at Kenwood and 

 Speigletown. 



Dicellograptus divaricatus Hall var. bicurvatus nov. 



Plate 18, figure 8 



This form possesses slower growing branches, acutely concave axils, 

 and a tendency to bend abruptly, from 2 to 5 mir. from the sicular extremity, 

 into slightly convex, less widely diverging, rather flaccid branches. The 

 thecal apertures appear to be a little more introverted than those of the 

 typical form and the first five to eight thecae of each branch are provided 

 with mesial spines, which are longest at the sicular end and gradually dis- 



217 2I8 



219 



Fig. 216 Dicellograptus di- _ Fig. 217-19 Dicellograptus d i v ar i cat us var. sa 1 o p- 



varicatus var. bicurvatus nov. iensis Elles & Wood. Enlargements (x 5) of portions of 



Sicular portion of type of variety [pi. branches: P'igure 217, of proximal portion of original of plate 18, 



18, fig. 8] enlarged x 5 figure 6. Figure 218 of portion of that of plate 18, figure 5 ; figure 



210 of fragment presumably belonging here 



appear in distal direction. The V-shaped axil is especially characteristic of 

 this variety, which we propose to name D . divaricatus var. bicur- 

 vatus. This form is the most common representative of the species at 

 Glenmont and at the Normanskill. 



Dicellograptus divaricatus Hall var. salopiensis Elles & Wood 



Plate 18, figures 5, 6 



Dicellograptus divaricatus var. salopiensis Elles & Wood. Monogr. Brit. 

 Grapt. pt 4 (Pal. Soc. 1904) p. 145; pi. 20, fig. 7a-e 



Elles and Wood have distinguished a variety as salopiensi s which 

 "is characterized by its slender stipes, which have throughout their extent 

 a uniform width of .5 mm only. The thecae are of the same general type 

 as those of I), divaricatus, and number 12 to 10 in 10 mm." It occurs 

 in the Glenkiln beds of Shropshire and of south Scotland. A like variety 

 occurs here in the Normanskill shale at Stockport and Kenwood. 



