58 PARTIAL ORISMOLOGY. 



maxillary palpi have never more than six, and the labial palpi but 

 seldom so many as FOUR joints. In every order a certain relation 

 between their numbers appears to be followed, to which, however, there 

 are a few exceptions. In the Colecptera, for example, the maxillary palpi 

 have very generally four joints the labial palpi three j in the Orthop- 

 tera, the former five the latter three ; in the Hymenopteret, the former 

 six the latter four, but with very many exceptions, particularly in 

 the maxillary palpi ; for example, Sirex has but one joint. Among 

 the Neuroptera these numbers are five and three ; among the Lepidop- 

 tera, two, or more rarely three joints in both ; the Diptera have one, 

 two, or four joints. The Hemiptera are destitute of palpi ; but if the 

 jointed sheath of the promuscis may be considered to represent them, 

 we shall also here very generally find three or five joints. 



The most usual shape of the feelers is FILIFORM (palpi jilifurmes, 

 PI. IV. f. 12, a) ; that is to say, such which have all their joints of an 

 equal cylindrical shape ; MONILIFORM (p. moniliformes), when the joints 

 are globose, like beads ; SETACEOUS (p. setace.'i), when tolerably long 

 palpi become gradually thinner, and the last is pointed. On the con- 

 trary, they are CONICAL (p. conici, PI. IV. f. 13, a}, when the joints are 

 very short, and each successive one is smaller than the preceding (the 

 Curculionodea]. The greatest differences, nevertheless, proceed from 

 the form of the terminal joint, for the first ones are almost invariably 

 cylindrical or ovate, and the last only differs in its form. We have 

 thence the following designations : 



SECURIFORM (p. securiformes, PI. IV. f. 14), when the last joint 

 is broadly triangular, and hangs by a point to the preceding (Securi 

 palpata} . 



LUNATE (p. lunati, PI. IV. f. 15), when the same joint has the form 

 of a half-moon (Oxyporus). 



FASCICULATE (p.fasciculati, PI. IV. f. 16), when it is split into 

 many threads and processes (Lymexylon). 



LAMELLATE (p. lamellati, Pi. IV. f. 17), when they are divided 

 longitudinally or transversely into several leaves (Alractocerus}. 



SUBULATE (p. subulati, PI. IV. f. 19), when the last joint forms 

 with the preceding a fine and delicate termination ( Trechus). 



CLAVATE (p. clavati, PI. IV. f. 20), when the whole organ becomes 

 thicker towards its apex (Trox). 



WEDGE-SHAPED (p. cuneif onnes}, when the last joint has the form 

 of a wedge, which is attached by its sharp end to the preceding joint 

 ((.'arabus, Calo oma, Cychrus, PI. III. f. 16, t). 



