MONOGRAPTUS. 



401 



Var. semispinosus, nora. nov. Plate XXXIX, figs. 4- a — c. 



1900. M. chhmvra var. a, Wood, Quart. Journ. Geol. Soc, vol. Ivi, p. -173, pi. .\xv, fig. 20. 



This variety bears precisely the same relation to M. chimseni that var. iacqjiens 

 does to M, lelntwardinensis ; it differs from M. cliimxra in being somewhat 

 broader (2'5 mm.), and above all in having the distal tlieca3 devoid of spines 

 altogether, while the proximal theca3 are spined in the usual manner. 



Horizon and Localities. — Lower Ludlow Shales (zone of M. scauicus). 



Ludlow District : Elton Lane; Elton-Ludlow Eoad. 



Var. semispinosus is onl}^ found in the zone of M. scaulctis, where it occurs in 

 association with the zone fossil and M. varians var. 'pumilns. 



Collections. — Lapworth and Wood. 



Monograptus leintwardinensis, Hopkinson MS. Plate XXXIX, figs. 8 <(—f. 



1880. Monograptus leintwardinensis, Hopkiusou (MS.), Lapworth, Auu. Mag. Nat. Hist. [5], vol. v, 



p. 149, pi. iv, fig. 1. 

 1884;. Monograptus leintwardinensis, J. D. La Touclie, Handbook to the Geology of Shropshire, 



p. 77, pi. xviii, fig. 574. 

 1897. Pristiograptus uncinatus, Freeh, Lethsea Geognostica, pt. iii, p. 058, fig. 213. 

 1900. Monograptus leintwardinensis. Wood, Quart. Jouru. Geol. Soc., vol. Ivi, p. 474, text-fig. 19, 



pi. XXV, figs. 21 A, B. 



Figs. 268 a — c. — Monograptus Icintivardi- 

 nensis, Hopkinson. 



i 



4 



:? 



Polypary short, seldom exceeding 1'3 cm. in 



length, straight distally, but with slight 



curvature in the proximal portion, increasing 



gradually in width until the maximum 



breadth of 1'6 mm. is attained. Thecae 



spined, fourteen to fifteen in 10 mm. ; those 



of the distal portion fairly short tubes with 



a length of about 2 mm., and about three 



times as long as wide, overlapping one-half 



to tAvo-thirds their length ; those of the 



proximal portion with slight ogee curvature 



and retroverted and spined apertural margins. 



Descrijjtion. — The polypary is always short and 



narrow ; it widens gradually for the first five or six 



theca3 and has then attained its maximum breadth, 



Quai-iy, Leintwardine ; Lower Lud- wliicli is maintained to the distal extremity. 



low Shales. Coll. Lapworth. . _ _ "^ 



f. Distal thecK, showing- paired spines. The sicula is loug and conspicuous I it measurcs 



On same slab as Plate XXXIX, . . 



figs. c-f. Lower Lndiow Shales. 2'1 mm. in length, exteudiuo: to midway between 



Coll. Fearnsides. . f 



the apertures of th. 2 and th. 3. 





is* 



a. Complete specimen, showing- sicula. 



Enlargement of part of Plate 

 XXXIX, fig. 8 a. 



b. Complete specimen, showing various 



positions of thecal spines. Figured 

 Quart. Journ. Geol. Soc, vol. Ivi, 

 p. 474, fig. 19 f-. Chiu-ch Hill 



