454 MERISTIC VARIATION. [part i. 



fin doubled. The deformed fishes were separated from the others but did not 

 produce a greater proportion of varying offspring than the normals (Ann. Maq. 

 N. H., 1842, p. 533). 



For a magnificent series of plates illustrating the various forms of Gold- 

 fishes see Billardon du Satjvignt, Hist. nat. des Dorades de la Chine, Paris, 1780. 

 [In Brit. Mus. copy text wanting ; I do not know if it ever appeared.] 



Fig. 142. Melolontha vulgaris, the Cockchafer, two cases of division of prono- 

 tum. (After Kraatz. ) 



1 With these cases compare the following : Hydrobius fuscipes, specimen 

 having pronotum formed into three lobes, one being central, and two lateral. The 

 lateral lobes projected from each side as considerable expansions. Kraatz, G.,Deut. 

 ent. Ztschr., 1889, p. 222, fig. 21. 



Division of median structures in Coleoptera. 

 The following list includes every case known to me. 



I. Epistome. 



692. Anisoplia floricola (Lam.) : Algerian specimen having the 

 epistome {chaperon) completely divided into two parts in the middle 

 line. Attention is called to the fact that this is a normal character 

 in certain genera of Lamellicorns, for example, Diphucephala and 

 Inca. Fairmaire. L., Ann. Soc. ent. France, 1849, Ser. 2, vn. 

 Bull., p. LX. 



II. Pronotum 1 . 



In Coleoptera the pro-thoracic shield or pronotum is normally 

 a single plate continuous from side to side. The following is a 

 list of cases in which this structure was composed of two lateral 

 parts. In Nos. 695 and 706 the division was not completed 

 through the whole length of the shield. The two halves were 

 in most cases symmetrical, but in Nos. 700 and 703 they were 

 unequal. 



As is shewn by No. 704 &c, there is in these variations more 

 than a mere fault of union between two chitinous plates, for in 

 this case the adjacent or inner edges of the plates were beset 

 with yellow hairs such as occur on the anterior and posterior 

 margins of the normal pronotum. In No. 703 again the adjacent 

 edges of the two plates are everted and form definite margins. 



693. Melolontha vulgaris (Lam.), prothoracic shield consists of 

 two symmetrical pieces which do not meet in the dorsal middle 

 line. The prothorax is greatly reduced in length and the head con- 

 sequently is almost in contact with the scutellum (Fig. 142, I). 

 Kraatz, G., Deut. ent. Ztschr., 1880, p. 341, PL n. Jig. 8. 



( 



