1954 ] 
Gregg — Distribution of Myrmoteras 
23 
prey cause the mandibles to snap shut, impaling small in- 
sects or other arthropods within their grasp. The closure 
is affected by powerful mandibular muscles, and the en- 
largement of these muscles has caused a protrusion and 
elongation of the occipital region of the head for their ac- 
commodation. The retrosalient behavior is attributed by 
Creighton to the effect of the mandibles snapping shut 
upon some object too hard and too large to be included in 
their bite. It is an ecological by-product, and he believes 
has no true functional significance in the lives of these ants. 
Field observations on Myrmoteras are extremely scant, 
and so far no one has seen the feeding activities or retro- 
salience in any of the species. It can only be inferred from 
the structure of the Myrmoteras head and jaws, and the 
presence of long trigger hairs, that the behavior is similar 
to that known to occur in the various other trap-jawed gen- 
era mentioned above. 
Wilson (1953) has recently added considerable interest- 
ing information about the feeding habits of North Ameri- 
can dacetine ants, and has confirmed the previously 
described hunting behavior of these ants in which the prey 
(Collembola and a few other arthropods) are caught by 
the convulsive snap of widely opened mandibles. 
Thus we appear to have some remarkable cases of con- 
vergence associated with trophic adaptations among ants. 
Two genera in the Ponerinae, a number of myrmicine 
genera, and one in the Formicinae have evolved indepen- 
dently food-seizing mechanisms of astonishing similarity, 
and these analogies are adequately described and illustrated 
in Creighton’s account. A fertile field of ecological and 
behavioristic studies is available for any myrmecologist 
with the opportunity to observe Myrmoteras in its natural 
habitat. 
The following is a description of a new species belong- 
ing to this genus. 
Myrmoteras karnyi sp. nov. 
Worker: Length 3.6 mm.; head index 0.92 
Of the seven species heretofore recognized in the genus, 
Myrmoteras karnyi is most closely related to M. hinghami 
by virtue of possessing a frontal furrow and by the pres- 
