524 



MISS G. L. ELLES ON THE GEAPTOLITE [Aug. 1 898, 



(63 mm.), and a maximum width of i inch (4-2 mm.), while other 

 specimens | inch (12-7 mm.) long and -i^- inch (1-26 mm.) wide 

 are also met with. There is a subsequent diminution ia width 

 near the distal end : this is shown in Prof. Nicholson's specimen, 

 figured in Geol. Mag. 1890. 



The best specimen that I have observed is 1| inch (38 mm.) 

 long; the width near the proximal end 

 is -^ inch (1'58 mm.), but this increases 

 steadily up to a maximum of -^^ inch 

 (4' 76 mm.), and is then broken off. The 



Pig. 34 



Trigonograp- 

 tus ensiformis, coll. 

 Woodwardian Mus. 



[X5.] 



width is trebled within the first ^ inch 

 (12-7 mm.) 



The thecae are twenty-eight to the inch 

 near the proximal end (eleven in 10 mm.), 

 but only twenty-four in the fully-deve- 

 loped part of the rhabdosoma (nine to ten 

 in 10 mm.). They are in contact for their 

 whole length, and have oblique apertures ; 

 these are markedly alternate on either 

 side of the rhabdosoma. They are in- 

 clined at an angle of about 45°. 



There is a very peculiar proximal exten- [^^^' size.] 

 sion from what appears to be the sicula ; 

 the exact nature of this I have not been able to determine. 



In one of the specimens the position of the virgula is clearly 

 indicated. It would seem to have been straight. 



Locality and Horizon. — Mosedale Beck, near Troutbeck ; 

 Ellergill Beds = Upper Skiddaw Slates. 



(h) Trigonograpius lanceolatus, jS'ich. 



1869. Trigonograpsus lanceolatus, Nich. Ann. Mag. Nat. Hist. ser. 4, vol. iv, 

 p. 232 & pi. xi, iig. 6. 



The only specimens of this species known to me are in Prof. 

 Mcholson's collection. The form is closely related to the fore- 

 going species, but diff'ers in the higher angle of inclination of the 

 thecae ; this is usually about 75°. 



The species widens rapidly from its proximal end, and the thec{£ 

 are markedly alternate. 



Locality and Horizon. — Upper Skiddaw Slates; EUergill, 

 near Milburn. 



Genus Thamnograptus, Nich. 



Thamnogeaptus Doveri, Xich. 



1875. Thamnograptus Doveri, Nich. Ann. Mag. Nat. Hist, ser. 4, vol. xvi, p. 271 & 

 pi. vii, fig. 1. 



The type-specimen is in the Woodwardian Museum. I have 

 nothing to add to Prof. Nicholson's description. 

 Locality. — South-western side of Eandal Crag. 



