PEEDACEOUS GROUND-BEETLES. 43 



A. Body of tho usual oblong form ; niesosternum and scutellum distiuct. 



B. Thorax Tvitli a sharp lateral margiu ; tibi;« without notch ; last joint of palpi large and tri- 

 angular ; eyes moderate, size usually large. 

 C. Size large ; elytra with numerous stritC. 

 » D. Head of ordinary form ; epipleura narrow. * 



E. Third joint of the autennie cylindrical ; color mostly black Carabus, 11. 



E E. Third joiut of antenna-, flattened ; body with rich metallic tints Calosoma, 21. 



D D. Head narrow ; epipleune very wide Cycheus, 25. 



C C. Size medium or below ; ely tral strise not exceeding nine ; color black Nebria, 18. 



B B. Thorax without a sharp lateral margin ; tibias with a small notch and with one of the 

 spurs at a distance from the apex ; last joint of palpi moderate ; eyes very large ; size 

 small. 

 F. Thorax almost cylindrical, without salient margin, and much nan'ower than the ab- 

 domen ; elytra with round shallow pits Elaphrus, 10. 



F F. Thorax depressed with an obtuse margin, nearly as wide as abdomen; color 



bronze-black Notiophilus, 8. 



A A. Body almost orbicular ; niesosternum covered by the prosternuni ; scutellum wanting ; colors 

 variegated O mofhron, 9 . 



Sub-family SCAEITIDES. 



The most conspicuous character of this sub-family is the peduncu- 

 lated abdomen, producing a separation between it and the thorax, 

 [Fig. 10.1 whence this section was called Bipartiti by Latreille But 

 the most essential and unexceptional character is the form 

 of the anterior tibae, which are widened and flattened, 

 and toothed on the outer side, and with the outer angle 

 .Drolonged into a long point. This structure enables these 

 nsects to dig in the earth, a habit expressed by the name 

 if the typical genus Scarites of Fabricius, meaning a 

 scratclier. The sub-family is also remarkable for the ex- 

 scarites (Aspiui- treme disparity in the size of its species, Pasimachus 

 5Sioit-rft.Eiiey.^6i"8' usually an inch or more in length, and Dyschirius 

 less than an eighth. The anterior tarsi of the males are very rarely, 

 and then but slightly dilated. 



A. First joint of antenna} elongated. Size comparatively large. 



B. Thorax with the hind angles prominent. Size large, or very large. Elytra usually -with 



ablue border Pasimachus, 14 



BB. Thorax rounded behind. Size medium, or above Scarites, 3 



A A. First joint of antennae moderate. Size small, or very small. 



C. Thorax somewhat square-shaped ; abdomen elongate and depressed CLmtfA, 35 



C C. Thorax sub-globose : abdomen ovoid Dy.schirius, 38 



Pasimachus is an exclusi^'ely Nortli American genus. The P. margi- 

 natus of Bonelli, and the P. ehngatus^ LeConte, are common insects, 

 usually found under stones or old logs. Dr. LeConte has given some 

 interesting details of the habits of the larva of P. elongatus, which 

 digs a deep hole in the ground, resting with its head at the entrance, 

 and springing upon any prey that may come within its reach, thus re- 

 sembling in its habits the larviB of Cicindela. 



* The ex)ipleura is the margin of the wing-cover which is bent abruptly downwards, and covers the 

 side of the abdomen. 



I' 



