132 



BRITISH GRAPTOLITES. 



Fig. 79 c. — Nemagraptus gracilis, var. 

 nitidulus (Lapw.). 



Distal thecae. Enlargement of part of 

 PI. XIX, fig. 4 a. 



(crossing canal) is horizontal, as in most Nemagrajpti, and thus in the reverse 

 aspect of the polypary there is the usual appearance of symmetry in the 

 proximal end. 



The thecae are long and remote ; they number 

 seven in 10 mm. and are inclined at 10°, have an 

 average length of 2 mm., are six times as long as 

 wide, and free for three quarters of their extent. 

 They have only been observed on the main stipes. 

 Affinities. — Var. nitidulus differs from all other 

 known Nemagrajpti, except var. remotus, in the tenuity of its stipes and their 

 extreme flexibility. From var. remotus, however, it may be distinguished by the 

 presence of only one branch arising in close proximity to the sicula. In the 

 diminution of the capacity for branching var. nitidulus approaches the Nemagnqjti 

 of Group II. 



Horizon and Localities. — Upper Llandeilo (Glenkiln). 

 S. Scotland : Glenkiln Burn ; Hawkwood Burn ; Rein Gill. 

 Associates, etc. — Var. nitidulus is a somewhat rare fossil in the Glenkiln Shales 

 of S. Scotland, where it occurs associated with Nemag. gracilis, Nemag. exjplanatus, 

 Dicellog. sextans, Dvplograjptus, sp., etc. The type specimen and several good ones are 

 in Lapworth's collection, while a few are in the collection of the Geological Survey 

 of Scotland. 



"igs. 80 a and b. — Nemagraptus, sp. 



\ 



> 



/ 



a. Proximal extremity. Enlargement 



of part of PL XIV, fig. 5. 



b. Distal thecae. Enlargement of part 



of PL XIX, fig. 5. 



Note. 



Another form of Nemagraptus, of which only 

 one specimen has as yet been found, is in the 

 collection of the Geological Survey of Scotland, and 

 is characterised by its pendant form (PL XIV, fig. 5). 

 Each main stipe bears two secondary branches, and 

 the thecae number eight in 10 mm. 



Should more specimens be found proving the 

 permanence of this form, it might be separated as a 

 distinct species under the name of N. descendens. 



Horizon and Locality. — Glenkiln Shales. 



8. Scotia ml : Craiglure Lodge, Head of Stinchar. 



Group II.— Type N. exjplanatus. 

 Nemagrajpti in which the stipes are but slightly curved, and diverge from the 

 The secondary branches are few in number. 



sicula at a wide angfh 



