106 MALACODERMATA. 
The disk is thus divided into a series of pits and elevations; of the latter two frontal, 
three median, and two near the base transversely placed are most evident. ‘The elytra 
are half the body’s length, serially punctate subcorrugate. 
Fam. LYMEXYLONIDA. 
The position of this singular family has not been ever definitely settled. That the 
insects which compose it have very close affinities with the Lampyride, and especially 
with Phengodes, cannot be denied; and I believe that ultimately it will be placed in 
proximity to those genera. I am constrained to enlarge the limits of the family to 
admit some very curious species for which otherwise separate subsidiary groups 
would have to be erected; and I should include some groups already created, viz. the 
Pterotini and Mastinocerini of Leconte. These beetles with those here described of the 
genera Euryopa and Péorthodius have not, it is true, the remarkable maxillary palpi of 
the true Lymexylonide ; but the eyes are largely developed in some, and the antenne 
exhibit a vegetative, rudimentary structure. The excess of this structure in one pair of 
the cephalic appendages may very probably account for the want of it in the other 
pairs. 
Of Leconte’s family or tribe Mastinocerini I will only remark here that his genus 
Mastinocerus, represented by a small species from Texas, is not congeneric with the 
species described and figured by Solier in Gay’s ‘ History of Chili,’ pp. 441, 442, Taf. 10. 
fig. 11, in which (if the figure be correct) the tenth joint of the antenne is small, and 
the terminal joint biramose; but his genus Cenophengus is related to it in having the 
second and third joints short, without rami. 
The Lymexylonide proper consist of only three genera and of few species; but their 
distribution is as remarkable as their abnormal formation, every part of the globe 
having some representative. 
PTORTHODIUS. 
Caput exsertum. Oculi mediocres, subglobosi, laterales. Mandibule valide, falcate, apicibus acutis, haud 
dentatis; palpi maxillares articulo apicali leviter ad apicem incrassato oblique truncato, labiales apice 
ovato. Antenne 12-articulate, articulis secundo et tertio brevibus, quarto ad undecimum filamenta bina 
a basi emittentibus, apicali simplici. Prothorax vel opaca, pubescens (ramosi), vel nitida punctulata 
haud canaliculata (mandibularis). Elytra corporis dimidio plerumque longiora, apicibus dehiscentibus. 
Abdomen (maris?) segmentis septem, sexto emarginato, septimo longo angusto submucronato. 
Type Ptorthodius mandibularis. 
After a careful study of the characters given by Leconte for Cenophengus, Masti- 
nocerus, and Pterotus, I do not think it is possible to connect the species described 
here with either of those genera. It is not always easy without the microscope to 
count the joints of the antenne; but in the species I select as the type they are 
