GRAPTOLITES OF NEW YORK, PART 1 631 



and Loganograptus denotes the preceding stage where the unlimited for- 

 mation of branches in Clouograptus has become normally restricted to those 

 of four orders only. Normally a Loganograptus has hence 16 branches; 

 but impei'fect fixation to branches of four orders on one hand, and incipient 

 reduction to lower orders of branches on the other cause considerable 

 variation in the number of branches. Thus in our material of L. logani 

 there occur specimens with as many as 25 branches, there still being present 

 branches of the fifth order, while, on the other hand, EUes and Wood 

 mention specimens of the same species with but six branches where only one 

 fourth dichotomy has taken place. 



Logfanograptus logani Hall 



Plate 9. flsrures 8-6 



Graptolithns logani Hall. Geol. Sur. Can. Rep't. for 1857. 1858. p.ll5 

 GraptolithuB logani Hall. Canadian Organic Remains, decade 2. 1865. p.lOO, 



pl.9, fig.l-9;pl.ll,fig.7 

 Loganograptus logani Hall. N. Y. State Cab. Nat. Hist. 20th An. Rep't. 



1867. p,226 

 Dicliograptus logani Nicholson. Quar. Jour. Geol. Soc. 1868. 24:128 

 Loganograptus logani Nicholson. Monogr. Brit. Grapt. 1872. ptl, p.l09, 



fig.52c, p.llO 

 Graptolites (Didymograpsus) logani McCoy. Geol. Snr. Victoria. 



Prodr. Pal. Victoria, decade 1. 187i. p.l9 

 ?Loganograptn8 logani Etheridge jr. Ann. and Mag. Nat. Hist. ser. 4. 1874. 



14:4, pl.3, fig.l2 

 Non Loganograptus logani Etheridge jr. Ibid, pl.3, fig.ll ( = Gonio- 



graptus thureaui) 

 Dichograptus logani Herrmann. Geol. Mag. Dec. 3, 1886. 3:24 

 Cf. Dichograptus kjerulfi Herrmann. Geol. Mag. ser. 3. 1886. 3:22,23, 



fig.8 

 Loganograptus logani Ami. Geol. Sur. Can. Rep't. ser. 2. 1889. v.3, pt2, 



p.ll7k 

 Dichograptus logani Matthew. Roy. Soc. Can. Proc. and Trans. 1893. 



11:114 

 Loganograptus logani Gurley. Jour. Geol. 1896, 4:294 



