OXYNOTK i:i; kS HU 



does ■ i, a form found nowhere pi in the Cdte d'Or. 



Quenstedt's collection at Tiibingen is very fine, and hia descriptions and figures 

 indicate a full representation of species, thoug I is no( present. 



i ipuisand Dewalque show that the Luxemburg rocks contain several d 

 enl forms of tin 1 genus, though they are nol bo numerous as in South Germany 

 or England. Schlonbach Bhows that there is an obtui • borizon in North Ger- 

 many containing the usual forms, but only fossiUferoua in certain localities, ami 

 Brauns publishes similar results in his work. This horizon according to Schliiter 

 does not appear to have been represented in the Ten toburger Wald, unless his 

 ■ . I and tin- broken l><-<|> mentioned on page I s of bis work b< 

 sidered the equivalent of all the beds between the Angulatus and Raricostatus 

 >u- 

 T I glish fauna, according to Wright's " Lias Ammonites " ami tin' collec- 

 tions examined by me, has all the principal forms, and often very large shells, 

 nud there arc al-o. as in tin- Cdte d'Or ami Rhone basins, representatives of the 

 •lie modification of this genus, .1 ( tnoti. 

 ThU series had, therefore, a more general development in all the basins we 

 lered than any of the preceding Beries, hut in Bpite of this then- Beems 

 lerance of forms in favor of England and France. The unusual 

 ■fan early appearance of the radical species id. obtusum in tin- Luxem- 

 burg region should have its due weight, bu I tin- eviden fan equally early 



occurrence in tin 1 South German basin shows that .!</. obtmum probably made 

 its appearance as an autochthons upon the level of the Upper Bucklandi bed in 

 the South German basin, and was thence distributed. It is probable thai the 



equently met with i <■ favorable conditions in the Cdte d'Oi and in 



I ind than in any other bat 



< »\\ \<>in ERAS 



,/. tin- radical -y> peculiar series, appeared in 



inch • with Buch ■ l\ compressed and involute whorls in 



1 nany, the Cote d'Or, and England, thai one 



ding with contemporary migrants from some unknown fauna. 



With : this conclusion, however, it may be well to In- cautious. The 



morph appears between an adult of a Bpecies like 



This is indicated clearly by the 



the individual in I fttotum, and I 



i to show iii the pri id 111 the descriptions ol the 



• and -p. ■ " frith s highly accelerated 



il in such forms the departure from allied forms took place sud 



denly. In consequence of this abbreviated mode of evolution gaps were hit in 



which it is difficult to fill The evidence with n the connec- 



I I I ind the \ OUng form- of 'tofuttt, 



■ 



