PETALOGrRAPTUS. 279 



ture, in contact for nearly the whole of their length ; apertnral margin 

 slightly concave, everted in compressed specimens. 

 Description. — The well-known Bohemian species — Petalog. ovatus — is but 

 doubtfully represented in the British Isles. The specimen here figured (PI. 



XXXII, fig. 6) and provisionally referred to this 



Fig. 192. — Petaloc/raptus ovatus ° ^ 



(Ban-.). for in comes f rom Skelgill in the Lake district. It 



possesses the almost circular outline so character- 

 istic of the Bohemian species, but differs in the 

 Typical specimen of p. ovatus, natural character of the proximal end, the earlier thecae 



Sedgwick Museum. ° emia ° being longer, more curved and less horizontal than 



is usual. 



The sicula is relatively long, measuring 1"5 mm. in length and reaching to the 

 level of the third thecal pair. 



The thecae are very closely set, in the proportion of twenty-eight in 10 mm., 

 but there are generally only seven or eight in the entire length of the polypary. 



We figure here for comparison a typical specimen from Zelkovice, Bohemia. 



Affinities. — Petalog. ovatus is readily separable from all other Petalogra/pti by 

 its nearly circular form, the closely-set thecee, and their horizontal direction of 

 growth. 



Horizon and Localities. — Gala-Tarannon Shales. 



Lake District : Skelgill. N. Wales : Conway. 



Associates, etc. — Very few specimens of Petalog. cfr. ocatus are known from 

 Britain ; the best specimen comes from the Browgill beds of Skelgill, and was found by 

 Mr. W. A. Brend associated with Monog. Marri. It is now in the Sedgwick Museum. 



Collections. — Sedgwick Museum, and the Authors. 



Petalograptus minor, Elles. Plate XXXII, figs. 5 a — e. 



1893. Diplograptus palmeus, Tornquist, Structure of some Dipriouidie, Acta Univ. Lund., vol. 



xxix, pi. i, figs. 29—31. 

 1897. Petalograptus minor, Elles, Quart. Journ. Geol. Soc, vol. liii, p. 201, pi. xiv, figs. 17 — 21. 



Polypary always small, rarely exceeding 1 cm. in length, concavo-convex in 

 section, the convexity being on the reverse aspect; generally oblong in out- 

 line, with narrow rounded distal end; widening gradually from origin, and 

 attaining maximum width of about 3 mm. at a point midway between the 

 proximal and distal extremities. Thecal twelve in 10 mm., alternate, 

 having an average length of 2 mm., four and a half times as long as wide ; 

 inclined at 45° ; apertural margins slightly concave in profile view. 



Description. — The shape of the outline of the flattened polypary, and its 



