HOMALOLINUS. 473. 
showing some interesting points of variation. The head varies in its development, and 
in small individuals has the hind angles obtuse, and departs comparatively little from 
the shape normal in the Xantholinina. In the larger examples found in the State of 
Panama and Costa Rica the sides of the head have a concave emargination, and a 
specimen of this variety from Irazu is represented on our Plate. The extent of the 
red colour at the extremity of the hind body is also variable, there being in this respect 
two forms, which apparently are not found in company: in the first the penultimate 
segment is black at the base, its hind margin and the whole of the terminal segment 
being red; while in the second form the whole of these two segments is red ; all the 
Mexican examples belong to the first of these varieties, except the single example from 
Tuxtla, while in the more southern parts of our area the two forms occur about equally, 
not being, however (if I may judge from the labels attached to our specimens), found 
in company. 
2. Homalolinus flavipennis. 
Xantholinus flavipennis, Er. Gen. et Spec. p. 307°. 
Hab. Mexico}, Oaxaca (Sallé), Cerro de Plumas (/6ge). 
The three examples before me of this species indicate that the head may probably 
vary in shape like that of H. canaliculatus; so that importance must not be attached 
to Erichson’s describing the hind angles as obtuse. 
3. Homalolinus affinis. 
Elongatus, angustulus, depressus, nitidissimus, niger, elytris anoque rufis; capite medio canaliculato, utrinque 
sulcato, sulcis latis, posterius punctatis, subtus vage punctato. 
Long. 20 millim. 
Hab. Guatemata, Purula, San Gerénimo (Champion). 
This species is very similar to H. flavipennis, but has the terminal segment and the 
hind margin of the penultimate segment red; the elytra are almost impunctate, the 
punctures along the suture and on the disc being very indistinct ; the lateral grooves 
of the head are broad and indefinite behind, and exhibit some punctures ab out their 
termination, and there is also a scattered punctuation on the under surface of the head.. 
Only two examples have been met with. 
4. Homalolinus dilutus. 
Elongatus, angustus, depressus, nitidissimus, brunneo-testaceus, capite nigro ; hoc subtriangulari, medio cana-- 
liculato, utrinque latius sulcato. 
Long. 20 millim. 
Hab. Mexico, Parada (Sal/é). 
This species, though differing so much in colour from H. canaliculatus, is in other 
respects excessively similar thereto ; the short lateral grooves of the head, however, are 
BIOL. CENTR.-AMER., Coleopt., Vol. I. Pt. 2, July 1885. 3 PP 
