COLEOPTEUA. PETALOCERA. 195 



molar tooth, with transverse ridges; the maxillee [^fig- 19- 8.) arc at- 

 tached to the labium in the same line, with a strong geniculation be- 

 low the centre, and generally terminated by a single lobe ; two, how- 

 ever, exist in the larvae of Aphodius {^Jig- 19. 2.) and Trox. The 

 maxillary palpi 3- or 4-, and the labial 2-jointed. The structure of the 

 tropin of these larvit offers considerable analogy with the parts of the 

 mouth in the Orthoptera. The legs are robust, with four joints, ter- 

 minated by a strong hook {Jig. 19. lo. hind leg of the larva of the 

 Cockchafer). The nine pairs of spiracles are placed upon the pro- 

 thorax and eight basal segments of the abdomen. The anus is very 

 large, transverse, or longitudinal. In their internal anatomy, the 

 Petalocerous larvae (excepting Aphodius) vary considerably from those 

 of the Lucanidffi. Some of these larvae are several years in attaining 

 their full size ; they then form, in situations where they reside, an 

 oval cocoon, composed of earth, excrements, and morsels of gnawed 

 wood, &c., agglutinated together. The pupae are of the ordinary 

 form ; but the sheaths of the lower wings are rather longer than those 

 of the elytra. 



The larvae of the Lamellicorn beetles have formed the subject of an 

 elaborate memoir by M. De Haan, published in the Nouvelles Annales 

 du Museum, vol. iv., in which the external and internal structure of 

 the following species has been very completely investigated ; Oryctes 

 nasicornis (^fig. 19. 4.), O. Silenus, Dynastes (Scarabaeus), Hercules, 

 Dichotomus, ? Atlas, and Gideon, Cetonia osnea and aurata {Jig.].9. 11.), 

 Melolontha fullo and vulgaris (/%. 19. 5.), Trichius nobilis, Hoplia ? 

 Aphodius nigripes {fg. 19. l.) and conjugatus. The following sketch, 

 confined to the external characters, and excluding the Lucanidae, will 

 show the distribution of these larvae proposed by M. De Haan, in 

 which there are four chief types of form: — 



A. Maxillrc simple at the extremity. 



1. Head not so broad as the body. 



«. Anus ventral. 



a. Mandibles elongate. Oryctes. "l 



B. Mandibles dilated. Scarabasus (Dynastes). J 



h. ^nus terminal. Cetonia. 



2. Head as broad as the body. 



a. Anus bilobed. Melolontha. T 



h. Anus trilobed. I 



a. Superior lobe largest. Trichius. | 



6. Superior lobe smallest. Hoplia. J 



B. Maxilla- with two terminal lobes. Aphodius. 



The larva of Oryctes nasicornis (fig. 19. 4. after De Haan) has also 



o 2 



