GKAPTOLITK^> OF NEW iOUK. I'AKT 1 <:>9'5 



tural margin normal on the axis of theca (forming an angle of 15G" with axis 

 of branch). 



Position and localities. A single surface in the quarry beds (graptolite 

 bed 5, belonging to the zone with D. bifidus) was found to contain this 

 species in numerous specimens. The species has not been reported from 

 Canada. In Great Britain it occurs in the Upper Arenig of the St David's 

 and Lake districts (Middle and Upper Skiddaw 

 slates), in association with D. bifidus and 

 D i p 1 o g r a I') t u s d e n t a t u s . 



Fig-. 88 Didy mogi-aptiis nanus 



Remarhs. This form Avas originally described kfaTsi p°''"°» ^^ '^''^"^h. Deep 

 by Lapworth as a dwarf variet}- of D . i n d e n - 



t u s Hall (^recte d e n t a t u s ; see Freeh, Lethaea palaeozoiaa 1 :590), with 

 which it agrees in everything except size and number of thecae in a given 

 unit of length. While it is sufficiently distinct to be recognized as a species, 

 its close relationship to I) . de n t at u s Hall is undubitable. 



Brogger \]oe. cit. p.40] records the occurrence of a variety of 1) . d e n t a- 

 t u s at Ki'ekling near Christiania. This may also be a D . nanus. 



Didymograptus (Isograptus) caduceus Salter emend. Kuedemann. 



Plate la, figures 6, 7 



Didymograpsus caduceus Salter (^pars). Quar. Jour. Geol. Soc. 1853. 9:87, 



fig. la 

 D i dymograpsus caduceus Salter (j^ar*). Quar. Jour. Geol. Soc. 1863. 19:138, 



p.l37, fig.l3a 

 Graptolites (Didymograpsus) caduceus McCoy. Pal. Geol. Sur. Vic- 

 toria. Prodr. Pal. Victoria, decade 2. 1874. p.30, pi. 20. fig.3-5a 

 Tet rag rapt us bryonoides Hall ( D . caduceus Salter) Etheridge jr. 



Ann. and Mag. Nat. Hist, ser.i. 1874. 14:2, pi. 3, fig.3, 4 

 Didymograptus gibberulus Nicholson. Ann. and Mag. Nat. Hist, ser.4. 



1875. 16:271, pl.7, fig.3, 3a, 3b 

 Phyllograptus stella Hopkinson. Quar. Jour. Geol. Soc. 1875. 31:658, pl.34, 



fig. 6 

 Didymograptus gibberulus Moberg. Geol. Foren. Stocldi. Frn-li. 1891. 



13:221 



