192 WILLIAM MORTON WHEELER. 



referred to the Middle Miocene; Forster ('91) a species of CEco- 

 phylla from the Middle Oligocene of Alsace, and Heer ('49) and 

 Mayr ('67) two species from the Lower Miocene of Croatia. 1 

 More recently Cockerell ('20) described a species of this genus 

 from the Eocene of England, and he ('15) and Donisthorpe 

 ('20) three species from the Middle Oligocene of the same 

 country. The one, or possibly two, extant species of CEcophylla 

 are now confined to the hottest portions of the Ethiopian, Indo- 

 malayan, and Papuan Regions. Similarly the few extant species 

 of Gesomyrme.v and Dimorphomyrmex are known to occur only 

 in Borneo and the Philippines. 2 In the same regions and in 

 Burma we find the four species of Myrmoteras. Santschiclla is 

 known only from a single specimen taken in the Belgian Congo, 

 the species of the genus Opisthopsis are confined to the Aus- 

 tralian and Papuan Regions, and the Neotropical Region possesses 

 only one of these ancient large-eyed Formicines, Gigantiops. 

 This, as we have seen, has a rather limited range and is in all prob- 

 ability a true tropical relict, originally developed in and since 

 mainly confined to that portion of the ancient South American con- 

 tinent known as Archiguiana. All of the genera above mentioned 

 are forest ants and most of them are arboreal, but, as we have 

 seen, Gigantiops spends most of its time on the forest floor and 

 nests in small, partly decayed logs. Opisthopsis nests under bark, 

 in the ground or in earthen termitaria, and 1 may add that Dr. 

 F. X. Williams, who took the types of Myrmoteras williamsi 

 Wheeler in the Philippines, informs me that this ant nests in the 

 soil. From what we know, therefore, of the living and extinct 

 forms, we are justified in concluding that the large-eyed Formicinas 

 originated during the early Tertiary, or more probably during the 

 Cretaceous, and that the extant forms have since undergone little 

 or no modification, owing to the very stable ecological conditions 

 in which they were able to survive. Gigantiops, in particular, may 



1 Since the completion of this paper Professor Cockerell ('21) has described 

 a peculiar large-eyed ant from the Green River Eocene of Wyoming as Eoform- 

 ica eocenica. It seems to belong to the subfamily Fomicinae and resembles the 

 Australian Opisthopsis in the shape of the head and the position of the promi- 

 nent eyes. 



2 Since this paper was written I have published the description of a 

 Gesomyrmex (G. hoivardi) from China. 



