736 STAPHYLINIDA. 
This is a smaller and narrower insect than the Brazilian L. scoriaceus, and it is there- 
fore only the largest examples of L. molossus that could be mistaken for that species, 
and these may be readily distinguished by the mandibular structure; the molar tooth 
of the right mandible being in such examples of L. molossus of remarkably large size, 
subquadrate in form, and very prominent, and separated from the lower angular tooth 
by an extremely large interval; while on the left mandible there are three angular 
teeth beyond the molar mass instead of two as in L. scoriaceus. In L. molossus the 
front of the vertex is scarcely at all produced in the middle, the antenne are mode- 
rately long and slender, and there is not more sculpture on the ventral segments than 
in L. scoriaceus. 
We have received a large series of L. molossus, and, as a rule, it may be recognized 
by a glance at the mandibles. Small examples do not, however, exhibit the specific 
characters in any thing like so conspicuous a manner; in such specimens the mandibles 
are much shorter, and on the left the molar mass is very much reduced in length in the 
longitudinal direction ; the molar tooth of the right mandible is also greatly reduced in 
size, and separated from the lower or basal angular tooth only by a small angular interval. 
‘These variations are apparently in part regional; thus while nearly all of the twenty- 
five Mexican examples belong to the larger or typical form, there is not one of this 
form amongst the twenty specimens from Nicaragua and the provinces further to the 
south, and even when the individuals from the south attain the size of the large 
Mexican form, they still retain the mandibular structure of the smaller Mexican form. 
This would suggest that there are really two closely allied species mixed by me under 
this name ; but the mandibular structure in the smaller examples is not sufficiently 
stable for me to discriminate two forms amongst them with certainty, while in Mexico 
the small form seems quite certainly to be connected by gradations with the larger 
form. I have not traced L. molossus beyond our region, though the smaller and more 
slender examples greatly resemble an undescribed Colombian species, Z. angustulus *, 
which, however, has apparently always two approximate punctures on the vertex, thus 
resembling superficially the allies of LZ. mexicanus, under which name, indeed, I have 
received an example from M. Fauvel. 
6. Leptochirus edax. 
Nigerrimus, depressus ; abdomine segmentis ventralibus ad basin parum sculpturatis ; mandibulis sat elongatis, 
sinistra dentibus duobus tenacibus et proprius ad basin tantum tuberculis duobus munita, absque dente 
* Leptochirus angustulus, sp. n. 
Depressus, nigerrimus, abdomine subtus haud ruguloso; mandibula sinistra dentibus duobus tenacibus, denteque 
molari elongato, margine interno tridentato, dextra dentibus duobus tenacibus, denteque molari sat 
magno ; vertice in medio anterius punctis duobus approximatis. 
Long. 17 millim. 
Hab. Colombia, Venezuela (coll. Sharp). 
