490 



BRITISH GRAPTOLITES. 



fimhriaius, M. triavrjnlatus, Mesog. vukjiius, Climacog. Tornquisti and other forms. 

 It also ranges higher, namely into the base of the succeeding zone, where it is 

 found with M. lobiferus, M. li'iuafiihif<, Glijptog. sinuatus, Climacog. scaJaris, etc. 



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

 Lapworth, and the Authors. 



Monograptus (Rastrites) setiger, sp. nov, Plate L, figs. 3 a — d. 



Fio. 345. — Monograptus (Rastrites) 

 setiger, sp. nov. 



Polypary with slightly arcuate proximal end, but straight or with irregularly 

 curved distal portion. Thecge twelve in 10 mm., very long but closely set, 

 having in the distal portion an average length of about 5 mm. with inter- 

 spaces not exceeding *8 mm. 



Description. — There is no enrolling of the initial 

 portion of this species ; indeed, the proximal end in 

 its general characters approaches that of M. (i?.) 

 Linnsei, but is stiffer. 



The sicula has a length of 1 mm., and the 

 earliest theca is short, not exceeding 1 mm. in 

 length. 



Bach succeeding theca is, however, longer than 

 the preceding one, th. 7 measuring 3'5 mm., and th. 

 12, 4*5 mm., so that the maximum length is rapidly 

 attained and thereafter remains constant. The 

 thecge are generally disposed perpendicularly, and 

 are of approximately uniform breadth throughout 

 their extent, with abruptly truncated apertural 

 terminations. 



Affinities. — The characters of the thecae, their length and proximity to each 

 other combine to make this species ensily distinguishable from all others except 

 M. (R:) longlsjmius, and from this species the form of the proximal end serves as a 

 ready means of separation. 



Horizon and Localities. — Llandovery (zone of M. gregnritis; sub-zone of M. 

 fimbriatus) . 



Lake District : Skelgill. Wales : Pont Erwyd. 



Associates, etc. — Monog. (B.) setiger occurs at the base of the zone of M. gregarius 

 associated with M. atavus, M. fimbriatus, and M. raif-:](ainiensis. 



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



/ 



Proximal portion, showing part of 

 sicula. Enlargement of part of 

 PI. L, fig. 3 a. 



