MONOGRAPTUS. 



489 



Associates, etc. — Mouog. (U.) peregrlnus, as restricted above, is not as a rule 

 very abundant in S. Scotland, though occasionally slabs covered with remains of 

 scores of individuals have been met with. At the lower horizon it is commonly 

 associated with M. gregaruis, M. triaugnlatus and Gli/ptog. tamariscus, while at 

 the higher, it is found with M. convolatiis, M. lohiferus, M. Clingani, M. limatulus 

 and other forms. 



Cullections. — Belfast Natural History Museum, Sedgwick Museum, Lapworth, 

 and the Authors. 



Monograptus (Rastrites) longispinus (Perner). Plate L, figs. 2 a — g. 



1897. Rastrites peregrinus vai*. loncjispinus, Perner, Grapt. de Bolierae, iii a, p. 9, fig. 7 ; pi. xiii, 



figs. 32 aud 35. 

 1907. Rastrites longispinus, Toruquist, Rastrites and allied species of Monograptvs, Lunds Univ. 



Arsskr., n.s., afd. 2, iii, no. 5, p. 10. 



Figs. 344 a and b. — Monograptus 

 {Rastrites) longispinus (Perner). 



Polypary arcuate, with broadly recurved proximal portion approximately semi- 

 circular in form. Thecse seven or eight in 10 mm., very long in propor- 

 tion to the width of the interspaces, 3 — 5 mm. in length, set more or less 

 perpendicularly, with interspaces measuring about 1 mm. in extent, and 

 distinctly reflexed apertnral terminations. 



Description. — The polypary is somewhat larger 

 than that of M. {R.) peregrinus and the shape of the 

 proximal end approaches that of a semicircle, being 

 very broadly recurved. 



The thecse are conspicuously long in proportion 

 to the width of the interspaces and frequently attain 

 a length of nearly 5 mm. The width of the inter- 

 spaces, though somewhat variable, usually averages 

 about 1 mm. in extent. 



Affinities. — Monog. (R.) longispinus bears a cer- 

 tain amount of resemblance in its distal portion to 

 M. (B.) setiger but has a differently shaped proximal 

 end. From other allied species it may be distin- 

 guished by the length of the thecse. 



Horizon and Localities. — Llandovery (zones of 

 M. gregariiis and M. convolntus). 



S. Scotland : Dobb's Linn. Lake District : Skel- 

 gill. Wales: Eheidol Gorge, Pont Erwyd ; 440 yards S.S.E. of Bryn-cliwith 

 Farm, Pont Erwyd. 



Associates, etc. — Monog. (Z?.) longispinus makes its appearance at the very base 

 of the zone of M. gregarius, in the sub-zone of M. fimhriatns associated with M. 



a. Proximal portion, showing sicula 

 and thecae. Enlargement of part of 

 PI. L, fig. 2 a. 



h. Distal theciB, partly in relief, show- 

 ing reflexed apertnral terminations. 

 Enlargement of part of PI. L, fig. 2 g. 



