492 



BRITISH GRAPTOLITES. 



Collections. — Geological Survey of England and Wales, Sedgwick Museum, 

 Lap worth, and the Authors. 



Monograptus (Rastrites) approximatus, var, Geinitzi (Turnquist). Plate L, 

 fig's. 5 a — (7. 



Figs. 347 a and b. — Monograptus (Ras- 

 trites) approximatris, var. Geinitzi 

 (Tornquist). 



1907. Rastrites approximatus, var. Geinitzi, Toruquist, Rastrites and some allied species of Mono- 

 graptus, Lunds. Univ. Arsskr., n.s., afd. 2, iii, no. 5, p. 9, ](1. i, figs. 32 — 41. 



Polypary with convolute proximal extremity. Thecge on the convex margin, 



twelve to ten in 10 mm., having a maximum length of 4 mm., and with 



interspaces averaging only 1 mm. 



Description. — The shape of the polypary is characteristic, both of the typical 



species and its variety. They are both more markedly convolute than any other 



forms included in this group. 



'i^he thecge are not very long, since none seem to exceed 4 mm. ; and- the 



interspaces separating them are small, so that the 

 thecse appear to be closely set. In the proximal 

 portion the thecse increase steadily in length from 

 •6 mm. in th. 1 to 2 mm. in tli. 4, and thereafter 

 the increase goes on steadily until the maximum 

 width is reached. "Phleoid" appearances are of 

 fairly frequent occurrence in this variety (fig. 347 h). 

 Tlie sicula has a length of at least "7 mm., and 

 th. 1 arises near its apex. 



Affinities. — The convolute proximal extremity is 

 possessed by both the typical species and its 

 variety ; but Tornquist has rightly separated the 

 form here described on the ground that its thecae 

 are about twice as long as those of the typical species. 



Horizon and Localities. — Llandovery (zones of M. gregarius to M. 8edgwiclci). 

 S. Scotland: Dobb's Linn; Belcraig Burn, etc. Ireland: Coalpit Bay, Dona- 

 ghadee. Wales : Parys Mountain, Anglesea; 430 yds. S.S.E. of Bryn-chwith Farm, 

 Pont Erwyd. 



Associates, etc. — This variety is quite common ; it occurs abundantly at the 

 lower horizon with M. ffregarius, M. triangidatus and Climacog. Tornquisti, with 

 M. convolutus, M. lohiferns, M. Clingani in the zone of M. convolutus, and with 

 M. Sedgwichi, M. tenuis and CI. scalaris at the top of the Llandovery. 



Collections. — Geological Survey of England and Wales, Sedgwick Museum, 



a. Proximal portion, showing sicula. 

 Enlargement of part of PI. L, fig. 

 5 6. 



b. Distal thecae, showing " phleoid " 

 appearance. Enlargement of part of 

 PI. L, fig. 5 a. 



