1876.] 7 [Austin. 



shorter than the head and thorax, with joints 8 — 10 longer than 

 wide, and the terminal one thickened. The elytra are a little longer 

 than the thorax, with the sides much rounded and a dusky orbicular 

 spot on the middle of each. The fifth segment of the abdomen is 

 dark, with the hind margin pale, and the terminal segment entirely 

 pale. 



9. Sunius similis. 



In this species the antennae are of about the same length as in the 

 last, but are much thicker, the joints 9 — 11, forming a club, the ninth and 

 tenth almost transverse. This species is much stouter than S. longius- 

 culus, and the elytra are shorter with no trace of a dark spot, and 

 the fifth and sixth segments of the abdomen are dark except at the 

 apex. Nev., S. Cal., and Ariz. 



10. Sunius trisignatus Boh., Ees. Eugen., 1858, 32. 



This species is closely allied to the preceding; the antennas are not 

 quite so much thickened externally, being intermediate between sim- 

 ilis and centralis ; the thorax is a little shorter, and the elytra a little 

 longer, so that they are about one-half longer than the thorax, and 

 have a faint spot on each. The fifth abdominal segment is black ex- 

 cept at apex, and the sixth has a fuscous tinge. San Diego (Coll. 

 LeConte). 



The species of Paederus are even more closely allied than those of 

 Sunius, particularly those in which the thorax and four segments of 

 abdomen are red. 



The following table will assist in separating the species: 



Head with a median smooth space, having at most a fovea on each 



side between the eyes, sometimes only a few punctures . 1. 



Head with a transverse flattened space in front between the eyes, 



mesosternum, two last segments of abdomen and knees black; 



elytra blue; large species (0.45 inch) . . l.femoralis'LQC. 



*• Thorax and four segments of abdomen red . . . .2. 



Unicolorous, red . . .5. 



Unicolorous, blue or black 6. 



Thorax red, rest of body dark blue or black . . . 7. 

 2. Very large species, size and form of femoralis 2. grandis n. sp. 

 Large species, head with a transverse fovea on each side be- 

 tween the antennas, leaving only a very narrow, median, 

 smooth space 3. riparius Linn. 



