GRAPTOLITES OF NEW YORK, PART 2 



(2 mm long) and broad, number i 2 to 14 in 10 mm and overlap one third 

 their length ; their ventral wall is highly convex in the distal part and the 

 apertural part strongly introverted and introtorted, lying within a deep, but 

 short round excavation, that occupies nearly one half the width of the branch 

 and one third the length of the theca. All 

 the thecae possess long, straight and rigid 

 mesial spines. 



Formation and localities. Hall's types 

 came from the Normanskill shale at the Nor- 

 manskill below Albany. Gurley reports it 

 from the outcrop of the same horizon at 

 Stockport and the New York State Museum 

 contains slabs from Glenmont which are 

 densely covered with this form. At Stockport 

 it is associated with Diplogr. angusti- 

 folius, Climacogr. parvus, Glos- 

 sogr. ciliatus, Dicranogr. ramosus, 

 Nemagr. gracilis and e x i 1 i s ; in 

 Glenmont with Didymogr. sagitti- 

 c a u 1 i s , Didymogr. subtenuis, Dip- 

 logr. foliaceus and Cryptogr. tri- 

 c o r n i s . It is also very common in a suite of 

 specimens collected by Walcott 2^ miles 

 north of Middle Granville, north of the Met- 

 tanee river. There it is associated with 

 Diplogr. foliaceus and Nemagr. 

 gracilis. Elles and Wood have described 

 a smaller variety of this species, D. furcatus var. minimus, which 

 they state to be fairly abundant in some of the Scottish localities of the 

 Glenkiln shales and to occur also in Ireland and Wales. 



Remarks. Hall's original drawings of D. furcatus which show 

 the characteristic aspect of the form, represent with one exception small 



Fig. 268-72 Dicranograptus furcatus 

 (Hall). Fig. 268, 26Q Ourley's manuscript 

 drawings of Stockport specimens. Nat. size. 

 Originals in National Museum. Fig. 270-72 

 Camera enlargements (x 5) of portions of 

 specimens from Glenmont, N. Y., showing tlie 

 form of the thecae 



