AMERICAN COLEOPTERA. 97 



space. This is well marked in the Helluonini, Pterostichna and 

 many Harpalini. The number of basal joints which may be glabrous 

 varies from two to four, but in Trachyj)achys there is no pubescence 

 whatever. 



It is extremely rare that the antennae are received in well marked 

 grooves on the under side of the head. The Pseudomorphinfe are 

 I believe the only instance of this. 



Labrum. — This member varies greatly in form and size. It is usually 

 transverse truncate in front or slightly emarginate, ciliate or with four or 

 six setae along the margin. It is rarely bilobed ( Ci/chrua, Dicrochile, 

 Zargus}, sometimes very large and convex {Anthid) or prolonged cover- 

 ing in great part the mandibles {FiricaluK, etc.). In some genera the 

 marginal setae may be very small, Anthia or entirely wanting, Macrn- 

 chilus and other genera of Helluonini. 



Mandibles. — These are variable in form and prominence, within 

 toothed, serrulate or simple. The tip is usually acute, the left mandible 

 overlapping the right. Sometimes however (certain Harpalini) the 

 mandibles meet in a pincer-like manner. The outer side is usually con- 

 cave, forming an elongate groove (called the scrobe), in which usually 

 beyond the middle is found a puncture bearing a moderate seta in 

 those genera of riparial habits {Nehria, Bembkh'inn, Fafrobuf, JVomius). 

 The presence of this seta is extremely important in defining the relation- 

 ship of genera otherwise obscure like Melsenns and Cose in ia. The scrobe 

 is, however, sometimes absent as in the genera allied to Feutagonka. 



Maxill.e. — In the present family the inner and outer lobes are 

 always present as will be observed in the figures ( it will be seen that the 

 outer lobe is absent in Dineutus, 151). The inner lobe varies somewhat 

 in form, it is usually hooked at. tip, the hook nevei' articulated. The tip 

 may however be obtuse without hook as observed ifi Scaritini (19, 21, 

 22), Promecognathini (18), Pterostichini (45), Cratocerini 

 (107), Orthogonini {Anoncopeucus), Peleciini (111), or more or 

 less acute, without hook as in Glyplus (133). The inner edge is ciliate 

 or spinulose and very rarely with anything approaching a tooth. The 

 outer or palpiform lobe is biarticulate (except in CoUistus 118, and 

 Amerizus 38), the joints of variable relative length, the two together 

 at least equal to the inner lobe, with the single exception of G/yptus 133, 

 where they are shorter. 



Of the maxillary palpi very little can be said in a general way. 

 The accompanying sketches represent every known variety of form. 



The maxillary lobes by their differences above mentioned afford merely 



TI?ANS. AM. ENT. SOC. IX. (20) JUI-Y, 1881. 



