294 



NEW YORK STATE MUSEUM 



Dicellograptus cf. complanatus Lapworth 



Plate 18, figure i 



Dicellograptus complanatus Lapworth. Ann. & Mag. Nat. Hist. Ser. 5, v. 5 



1880. p.r6o; pi. 5, fig. iya-e 

 Dicellograptus complanatus Tullberg. Sver. Geol. Unders. Afh. och Upps. 



Ser. C, no. 50. 1882. p. 18 

 Dicellograptus complanatus Roemer & Freeh. Lethaea Palaeozoica. 1897. 



1: 618, fig. 183 

 Dicellograptus complanatus Lapworth, Elles & Wood. Monogr. Brit. Grapt. 



(in Pal. Soc. 1904). p. 139; pi. 20, fig. ia-d 



A small series of graptolites collected by Dr Ulrich in dark brown 

 limestone (Sylvan shale), said to lie above the Richmond beds, in the 



Arbuckle mountains 

 in Indian Territory, 

 contains two proxi- 

 mal parts of rhabdo- 

 somes of a Dicello- 

 graptus which can 

 not be positively 

 identified since the 

 rhabdosomes are but 

 fragmentary, but 



which by their habit 

 remind of D. complanatus and of D. f orchammeri, especially the 

 former. The rhabdosome possesses the same wide axil, the same angle 

 of divergence (270 ), like gently outward curvature of the branches and 

 width of their proximal parts (.5 mm). The sicula is in both specimens 

 incompletely preserved, a peculiarity mentioned also of c o m p 1 an a t u s ; 

 the first thecae are nearly horizontal and bearing short, blunt, lateral spines. 

 Also some of the next thecae are provided with mesial spines. The thecae 

 appear to be, in their characters, entirely like; those of 1). complanatus. 

 The)' number 10 in 10 mm, are long and slender (2 mm long), overlapping 

 not quite one half their length, with straight or but slightly convex ventral 



Fig. 208,209 Dicellograptus cf. complanatus Lapworth. Enlargements (x 5) 

 of two fragmentary rhabdosomes 



