LATER MESOZOIC INVERTEBRATE FAUNAS 413 
concludes that there must have been direct marine connection with 
all these regions. The most striking example of the introduction of a 
new element in the fauna is the intercalation of a thin Aucella bed in 
the midst of strata containing the Mediterranean type of fauna in 
the upper Kimmeridgian. ‘The Aucella must have come in from the 
Pacific where, as we have seen, the boreal type of fauna extended at 
least as far south as middle California. The nearest recorded occur- 
rences of Aucella in the other direction are on the east coast 
of Greenland and in England. On the other hand this Mexican 
fauna as a whole is so unlike that of California and so related to 
that of Europe, and the geographic position of the beds is such 
that connection with the Gulf of Mexico seems most reasonable. 
The area should therefore be mapped as included in the Atlantic 
sedimentation though it is probable that the Pacific waters bearing 
the Aucella found temporary access to it from some point south of 
the Gulf of California. If the exact position of this temporary 
Pacific connection is still indicated by sediments they have not yet 
been recognized. 
Farther south in Mexico a somewhat different facies of the Upper 
Jurassic fauna found in the state of Oaxaca has been described by 
Felixt but according to Cragin? this has some species in common with 
the Malone Jurassic fauna of western Texas which on the other hand 
shows some relationship with the fauna of Catorce, San Luis Potosi, 
and hence also with that of Mazapil. The Malone fauna shows no 
connection whatever with the Rocky Mountain Jurassic because it 
belongs to a later stage and to a different province. It probably 
lived in an arm of the Gulf of Mexico directly connected with the area 
in Zacatecas and San Luis Potosi, and including the locality near 
Cuchillo Parado, Chihuahua, reported by Aguilera. Some of the 
elements of the Malone fauna show decided Cretaceous affinities 
and thus strengthen the evidence that it is latest Jurassic. 
In Europe Neumayr recognized three marine faunal provinces 
in the Jurassic which, as he believed, indicated climatal zones. ‘These 
are the Mediterranean or Alpine, the Middle European, and the boreal 
t Palaeontographica, Band XXXVII (1891), pp. 172-80. 
2U.S. Geol. Surv., Bull. 266, 1905. 
3 Apercu sur la geologie du Mexique, p. 8, 1906. 
