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



furnished with a spine, which probably is the apertural spine of the 

 sicLila ( = virgella of Tornquist), This varies in length in different 

 individuals ; it is usually short and about yL ^^^^ (^'1 mm.) in 

 length, but may be longer; it is stout at its origin, but tapers 

 quickly^ and is very slender at its termination. The virgula is often 

 clearly seen and is frequently prolonged for a considerable distance 

 beyond the distal extremity of the rhabdosoma. 



The thecae vary from twenty-eight to thirty-six in the inch (eleven 

 to fourteen in 10 mm.) ; in their normal aspect they are seen to be 

 inclined at an angle of about 20°, and are free for a third of their 

 length ; their apertures are slightly oblique. 



Occurrence. — Ellergill Beds = Upper Skiddaw Slates. 



Localities. — Thornship Beck; Aik Beck, Pooley; Troutbeck; 

 Ellergill, Milburn ; north-west of Longside, Skiddaw; Mosedale 

 Beck ; Mungrisedale ; Glenderamakin Biver ; Bassenthwaite Sand- 

 beds ; Outerside ; Master Sike, Crossfell. 



(h) DiPLOGEAPTUS Cf. TEEETIUSCULUS (His.). 



1881. Diplograptus teretiusculus, Tullberg, 'On Grapt. descr. by Hisinger, 

 Bihang til k. Svenska Vet. Akad. Handl. vol. vi. 



There are some specimens of Diplograjptus in the Skiddaw Slates 

 which seem to me to bear a very marked resemblance to Hisinger's 

 species ; they are certainly different from the species just described. 

 Unfortunately they are not sufficiently well preserved for all the 

 details regarding the cells to be made out. 



This form is commonly about an inch (25*4 mm.) long, and has a 

 maximum width of ^ inch (3*2 mm.). 



The thecae number twenty-two to twenty-four in the space of an 

 inch (eight to nine in 10 mm.). There is a short stout spine at the 

 proximal end (virgella). 



Occurrence. — Upper Skiddaw Slates. 



Localities. — North-eastern side of Souter Fell; Bandal Crag, 

 Skiddaw. 



(c) DiPLOGEAPTlJS APPENDICULATFS, Tomq. MS. 



Obviously this species is closely allied Eig. 30. — Diplograptus 

 to the well-known D. vesiculosus (Nich.), appendiculatus, coll, 



but is far more slender than that species. /. E. Marr. 



Near the proximal end, which is not 

 seen in this specimen, the width is -^ inch 

 (1"26 mm.) ; it gradually widens towards 

 the distal end to a maximum of -^ inch 

 (2*1 mm.). Prom the upper end proceeds 

 the vesicle, inside which the virgula can 

 quite well be detected. 



The thecae number twenty-four to the 

 inch (nine to ten in 10 mm.) ; their outer 



walls are slightly convex; they are inclined W -3 



at about 25°, and overlap for half their ^'* ^ 



length. Their apertures are perpendicular 

 to the general direction of the rhabdosoma. FN t " * 1 



