174 



BRITISH GRAPTOLITES. 



Dicranograptus cyathiformis, sp. nov. Plate XXV, fig; 



fo 



Polypary funnel- or vase-shaped, consisting of a short biserial portion about 



5 nun. in length, and two uniserial stipes which first run subparallel to each 



other for a distance of 1 cm., including between them an exceedingly small 



axillary angle, next make a sharp outward curve so as to include an angle of 



about 45° between their dorsal Avails, and finally are continued in a straight 



for a distance of 1 — 1'5 cm. Thecse twelve to nine in 10 mm. of the same 



general type as those of Dicranog. Nicholsoni. 



Description. — The biserial portion of the polypary is composed of 6 thecae or 



more on each side; it is narrow, and increases in breadth from "9 mm. at the 



proximal end to T5 — 2 mm. at the point of origin of the uniserial stipes. The 



uniserial stipes have an average uniform width of 1 mm. 



The sicula has not been observed, though its apertural spine is visible at the 

 Fig. no.-memnogmptuscyathi- extreme proximal end. The "lateral" spines of th. I 1 

 ls > nov - and th. I 3 are prominent. Small and inconspicuous 



mesial spines are present on all the remaining thecas of 

 the biserial portion, but they appear to be absent on 

 those of the uniserial stipes. The theca? in the biserial 

 portion are markedly alternate, and there are indications 

 of the presence of a septum. 



The thecae are far more closely set in the biserial 



portion, where there are twelve in 10 mm., than in the 



uniserial stipes, where there are only nine in the same 



Enlargement o'fpaxt of pi. xxv, unit of length. They have an average length of 1-5— 



fi s- 2b - 2 mm., and usually overlap for one third. 



Affinities. — The peculiar form of this species is sufficient to distinguish it from 



all other Dicranogrwpti. 



Horizon and Localities. — Glenkiln Shales, Lower Hartfell Shales (?). 

 S. Scotland.— Dobb's Linn; Hartfell Spa. 



Associates, etc. — D. cyathiformis is a rare fossil in the Glenkiln Shales of 

 S. Scotland, where it occurs associated with certain spinose Dvplograpti. A 

 specimen, probably referable to this species, has been found in the Hartfell Shales, 

 in the zone of Dicranog. Clingani. The best specimens known to us were collected 

 by Swanston, and presented by him to the Sedgwick Museum. 







