112 MODERN CLASSIFICATION OF INSECTS. 
the largest, and pilose ; the maxillary palpi long, slender, and 6-jointed ; 
the four basal joints gradually increasing in length; the fifth very 
minute, and the last as long as the third (fig. 71. 20.). Like the 
Uroceridee, the calcaria of the anterior tibie are single (fig. 71. 22.) ; but 
each of the tarsal joints is furnished with a minute membranous Icbe 
beneath. The intermediate tibiz have also one, and the posterior 
tibia, two spurs towards the middle (zg. 71. 23.), which, together with 
their multiarticulate antennz, indicate a relation with Lyda. The 
collar is elongated, as in the Uroceride ; the ovipositor consists of two 
compressed plates, nearly straight, and serrated, but formed as in the 
true saw-flies, defended by two external 2-jointed sheaths (fig. 7. 24. 
apex of abdomen of Cephus ¢ with the saws extended). 
The larva of the typical species C. pygmeeus (Sirex pygmeus Linn.) 
resides in the interior of the stems of wheat, and occasionally commits 
much injury. A memoir was published upon this insect by Bosc 
(Bull. Sciences Nat. No. 5. 1823, and see Philos. Mag. August, 
1823,) in which various means were suggested for its destruction. 
The larva is figured by Guérin (Jeonogr.). Another species (C. ab- 
dominalis, Zatr.) is stated by Latreille to live upon the flowering buds 
of fruit trees, and do them a great deal of mischief. M. V. Audouin 
has, however, informed me that it deposits its eggs on the young shoots 
of the pear in a spiral direction, and that the larva feeds within the 
slender shoots. (Aud. MSS. Obs. 1835, No. 9.) The larva (fig. 71. 
96., copied from Audouin’s highly magnified drawing) is fleshy, with a 
scaly head, and six thoracic minute legs, but destitute of anal prolegs ; 
the abdomen has the terminal segment attenuated and terminated by 
two minute points; there is also a minute conical lobe near the base on 
each side of this segment. The situation of this genus has been the 
subject of much discussion. Dr. Leach placed it in his family 
Xiphydriadz, and Klug and Hartig amongst the Siricide ; the latter 
being influenced by the form of the collar, saws, and anterior calcaria. 
Latreille united Xyela, Cephus, and Xiphydria into a distinct section 
at the end of the Tenthredinide. Curtis, from the form of the labium, 
elongated palpi, and spurred posterior tibize, arranged it with Tenthre- 
dinidee ; which I certainly deem its most natural relations, having more 
especially regard to the form of its larva and that of Lyda. 
The distribution of these insects had been attempted by various 
authors ; Leach, Klug, St. Fargeau, Dahlbom, and Hartig having de- 
voted much attention to this branch of the subject. Geoffroy first 
