656 NKW YOUK STATE MUSEHM 



Tetragraptws serra Barrois. Ann. de la 8oc. Geol. du Nord. 1892. 20:94 

 Tetragraptus serra Gurley. Jour. Geol. 1896. 4:295 



Tetragraptus bryonoides Romer & Freeh. Lethaea palaeozoica. 1897. 1:601 

 Tetragraptus serra Elles. Quar. Jour. Geol. Soc. 1898. 54:490 

 Tetragraptus serra Ruedemann. N. Y. State Paleontol. An. Rep't. 1902. 



p.554, 556, 566 

 Tetragraptus serra Elles, Wood & Lapworth. Monogr. Brit. Grapt. ptl. Pal. 



Soc. 1902. p.65, pl.6, fig.4a-f 



Description. Primary disk and neraa not observed. Sicula relatively 

 short (2 mm) and slender. First theca originating within apical third of 

 sioula. Branch of first order (first two thecae) short, about 2 . 7 mm long ; 

 four branches of the second order approximately straight, attaining a length 



of 30 to 50 mm, rapidly widening from . 7 mm to 



■^^^^ V ^^m the threefold and fourfold Avidth. Thecae 8 to 9 



^^J^^^fc^^^' in 10 mm, narrow (three to four times as long as 



^F ^^L wide), slightly curved, much inclined (40" to 45°), 



^m ^ overlapping for two thirds to three fourths of 



^^ their length. Outer thecal walls concave, aper- 



nrongniart s]i. Young rhabdosome. tural margin coucave, uormal on axis oi triecae. 



Obverse view. Deep kill. x4.5 



Position and localities. Brongniart's orig- 

 inal of the species came from Point Levis; and Hall based his description 

 on material from Quebec shales of Point Levis, Gros Maule and River St 

 Anne. The form is evidently very common in the Levis region; for Ami 

 cites it from a whole series of localities in that neighborhood. Gurley lists 

 T. serra as occurring in all three Quebec zones, the Main Point Levis 

 zone, the Phyllograptus anna zone and the Upper Levis zone. Besides, he 

 found it also in the suite submitted to him from Arkansas. Billings noted 

 the species among the graptolites from Cowhead, Newfoundland (division P). 

 In the preliminary paper on the Deep kill section, I reported this form as 

 being rare in graptolite bed 1, common in graptolite bed 2, as being found 

 in a small mutation in graptolite bed 3, and as passing through the 

 Didymograptus bifidus zone (graptolite beds 3 to 5). Tt occurs also associ- 

 ated with Diet yon ema murrayi, a species of Clonograptus and 



