IXTRODUCTIUN. 



FiK. 9. 



side a membranous appendage ; these ajipendages are termed jMraf/Iossur. 



in many genera tliey are very conspicuous, projecting far beyond the 



ligiila, but in some cases they are soldered to 



the sides of the hgula, and occasionally are 



not visible at all ; from supports situated at 



the base of the ligula, between the liguJa 



and mentum, arise the lahial jx^h^i '• these 



are usually 3-jointed, rarely 2-jointed, and 



occasionally, as in Myllcena, &c., setiform, 



not presenting the appearance of palpi at all. 



The mentum and ligula make up the labium : 



the terms ligula and labium, however, are 



used very loosely by many authors, Avho 



consider them as distinct from the mentum 



altogether, and speak of the labium as the 



basal portion of the organ in front of the 



mentum, the ligula proper being made up of 



the front portion, wdrich in some cases, e.g. Aulalia, is much extended, 



and appears to be distinct,' but is not really so. 



The comparative size of the joints of the labial palpi, and the number 

 of setse borne by them and by the anterior margin of the ligula are very 

 useful as affording generic characters in some cases. 



Labium of Pterostichus niger. 



I, Mentum. h. Ligula. c c. Pa- 



raglossas. d d. Labial palpi. 



The Thorax. 



Throughout this work the term " thorax " is used roughly for con- 

 venience sake for the upper portion of the body between the head and 

 the base of the elytra, the part in fact which 

 in common language is usually called the 

 thorax ; as a matter of fact, however, the 

 thorax is made up of three parts, the prothorax, 

 mesothorax, and metathorax ; the upper sur- 

 faces of these are called respectively the pro- 

 notum, mesonotum, and nietanotum, and the 

 under surfaces the pn'osteriinm, mtisosternum, 

 and metasternum : the so-called " thorax " is 



Pronotum of thorax of 

 D. marginalis. 



really the pronotum; the only portion of the a. Anterior margin. S. Pos- 

 mesonotum visible from above is the scutellum, tenor margin 

 which usiially appears as a triangular or semi- 

 circular plate between the two elytra at base, 

 but is sometimt's wanting ; the metanotum is 

 altogetlier hidden by the elytra. 



Tixe 2>'''odernum bears the front pair of h^gs ; it is often produced in a 

 longer or shorter, sharper or blunter process between them posteriorly : 

 this ^^ prosternal 2yroccss" as it is called, is often of great use in classi- 

 fication; the mesonotum and mesosternum, which make up the meso- 

 thorax, bear respectively the anterior pair of M'ings or elytra and 



c c. Lati'ral 

 margins, d. Dorsal, central, 

 or median line, e e. Ante- 

 rior angles. //. Posterior 

 angles, g g. Disc. 



