INSECTA. 



891 



^ Fig, 371. 



\ 



Antennae, from Burmeuter, Meigen, Paty, and Hope. 



M, antenna of Melolontha folio; 1, scapus ; 2, 



pedicella; 3, clavus ; 3*, the laminae. 



called setaceous (fg. 371, A), but when, as in 

 some of the Locwtida, each joint is much smal- 

 ler than the preceding and is angulated at its 

 sides, the whole forming a sword-like organ, 

 it is called ensifitrm (B). When all the joints 

 of the clavola are of uniform thickness, as in 

 the Carabida, (fg. 329,) the antenna is said 

 to be filiform (Jig. 371, C), but when the joints 

 are of equal size, but are globular or rounded, 

 as in the Tenebrionida (Jig. 340), it is called 

 moniliform (fg. 371, D). When the joints, 

 as in some of the Elaterid<e, (fg. 334,) ap- 

 pear like inverted triangles, with the inner 

 margin more produced than the outer, they 

 are said to be serrated (fg. 371, E), and 

 when, as in the Prionidx, the acute base of 

 each joint is inserted into the middle of the 

 broad apex of the joint behind it, imbricated 

 (F). When every joint is developed on one 

 side into a spine or process, tlie organ is said 



to be pectinated (G) ; and when a spine or 

 process is developed on each side of the joints, 

 bipectinated (H). In like manner it is called 

 plumose(N ) when each joint producesone or more 

 rami which are themselves minutely pectinated, 

 as in many of the Bornbycida; and when, as in 

 Hemirrhipusjlabellicornis and other Elaterid<r, 

 each process from a joint is flattened, and is 

 nearly as long as the whole of the succeeding 

 joints taken together, and the whole form a 

 fan-shaped organ, the antenna is called Jlabel- 

 Itite (I). But when, as in the true beetles, 

 Pentamera, the clavola ends in a true capi- 

 tulum or knob, it is said to be clavate (K), or 

 capitate (L), according as the knob is gra- 

 dually or suddenly formed at the extremity of 

 the organ. In Hydrous the capitulum exists 

 in that form which is designated perfoliate y in 

 which the joints of the club are separated a 

 little from each other by a minute foot-stalk. 

 This form exists also in the Necrophori, and 

 in a less degree in the clavated antennae of other 

 Silphidte. It is in some of the Lamellicomes t 

 the Scarabaida, Geutrvpida, Dynastida, and 

 Melolonthida, that the antennae reach a degree 

 of completeness which seems to indicate the 

 real use of the organs. Thus in the Melolon- 

 thidit (M), the capitulum is divided into seven 

 laminae, which may either be applied closely 

 together, or be widely expanded at the plea- 

 sure of the insect. In the Dynastida and 

 Geotrupida the capitulum is formed of only 

 three laminae, the two outer ones being convex 

 externally, but flat on their internal surface, 

 while the intermediate one is flat on both sur- 

 faces, the flat surfaces of each being more 

 delicately organized than the hard corneous 

 exterior. A similar structure exists also in the 

 Scarabaida. When the insect is in motion 

 the antennae are stretched out, and the laminae 

 are expanded to their fullest extent, but by 

 many species are immediately retracted on the 

 occurrence of any loud or sudden noise. 



These are the usual forms of the antennae, 

 but in some species they are subject to much 

 greater variation. Thus, in the remarkable 

 order Strepsiptera (fig. 347), each antenna has 

 a distinct lobe at its base. This is also the 

 case in some of the Muscida (N), in which the 

 filamentous portion of the antenna represents 

 the true clavola, and the club-shaped portion 

 of the organ is simply an appendage. A simi- 

 lar deviation from the usual structure occurs in 

 some Coleoptera, more particularly in the smal- 

 ler water-beetles. Thus, in the Gyrinida, the 

 true pcdicelUi is developed into a large ear- 

 shaped cup, which nearly covers the clavola. 

 In another insect, Globaria Leachii, LATR. 

 very beautifully figured in the recent work 

 of the Rev. F. W. Hope,* the pedicella, 

 (O, 2) instead of being a small rounded joint, 

 is elongated like the scapus (1), while the cla- 

 vola (3) ends in a large capitulum, attached 

 laterally to the base of the fifth joint and di- 

 rected backwards. These are a few of the 

 variations which occur in the form of these 



* The Coleopterist's Manual, part ii. tab. 3, 



fig. 6. 1838. 



