THE PSELAPHIDZ OF NorTH AMERICA. a to 
the side pieces not distinct, ankylosed, prosternum very narrow, 
often not visible between the coxe. Mesosternum very short, 
metasternum very broad. Elytra truncate, subtriangular. 
Abdomen with five dorsal and five or six ventral segments. 
The anterior coxe are prominent, conical, nearly contiguous, 
the intermediate rounded and near together, the posterior ones 
transverse, not prominent. 
The Pselaphidz proper are divided into three sections, the 
Pselaphini, Brvaxini, and Euplectini which sections become 
almost yearly more indefinite by the discovery of inter- 
mediate forms, thus demonstrating the unity of the present 
family. 
The Pselaphini were formerly considered a well defined 
section, but later discoveries such as the Bythinoid forms of | 
Macherodes, Eutrichites and Scalenarthrus link them with 
the Bryaxini. The genera Pselaptus, Verticinotus, and 
Eupsenius on one hand and Arthmius on the other lead from 
Bryaxis to Batrisus and the general form of the latter is 
repeated in Trimium. For want of a better place, the 
Trogasterini are placed between Trimium and Euplectus, as 
they exhibit radiating affinities. 
The species of the second section of Capt. Casey’s synopti- 
cal table are in our opinion not Euplecti. They stand between 
Euplectus and Trimium, nearer the latter, and have received 
the name Trimioplectus. 
The forms of Eutyphlus, Thesium and Faliscus approach 
_ the Faronii which latter we leave intact under the old genus 
Faronus for want of a more complete knowledge of the 
foreign members of this section. 
All of the Pselaphide live on animal substances, and the 
comparatively powerful mandibles and maxilla together with 
long palpal members seem to indicate that they capture fleet 
and hard-shelled prey. As a rule the Pselaphini live mostly 
in pairs while all the others are gregarious at least during the 
period of copulation when so-called “rare” species may be 
found in numbers. 
