bkeed: metamorphosis of the muscles of a beetle. 319 



based on dissections in which only imaginal forms liave been used. The 

 few exceptional cases in which larval forms have been used happen to be 

 dissections of larvae from orders of insects other than Coleoptera. The 

 best attempt that has been made as yet to establish the homologies of 

 the imaginal forms is that of Petri ('99), who has studied the muscular 

 systems of Trichoptera, Diptera, and Hymenoptera, On account of this 

 unsatisfactory state of the comparative myology, no attempt will be made 

 to homologize the muscles of Coleoptera with those of otlier orders. 

 Consequently, only those papers that deal with Coleoptera will be men- 

 tioned. A very good review of the whole ground is given by Petri ('99). 

 Of the three papers that deal with the imaginal muscular system of 

 Coleoptera, the monumental work of Straus-Diircklieira ('28), on Melo- 

 lontha vulgaris, is the first and most important. The nomenclature used 

 by him is, however, unsatisfactory, as it is not generally applicable. The 

 next paper in importance for us is that of Luks ('83), who gives good 

 figures and a short description of the thoracic musculature of Dytiscus 

 marginalis Linn. He finds the musculature much the same as in 

 Melolontha, with the exception of the coxal muscles of the metathorax. 

 Owing to the firm fusion of the coxae to the metasternum, the func- 

 tions of the coxal muscles have changed. These muscles serve either 

 as indirect wing muscles, or as flexors or extensors of the trochanter. 

 The Latin nomenclature used by him is founded principally on the func" 

 tions of the muscles. It is the best nomenclature available, and is there- 

 fore used as far as practicable in this paper. When the homologies shall 

 have been made clear, probably a modification of the nomenclature of 

 Amans ('85), founded on the attachments and positions of the muscles, 

 will be used for all orders of insects. In his paper, Amans gives a short 

 description of the wing muscles of beetles.. 



Observations. 



1. Material. 



The principal material used has been Thymalus marginicollis Chevr., 

 one of the Trogositidae. Marginicollis (Chevr. 1842) is used as the 

 specific name of this species by the authority of Leveille ('88), who, in 

 his catalogue of the Temnochildes (=Trogositidae), substitutes this name 

 for fulgidus (Erich. 1844), the name in most common use. Inasmuch as 

 marginicollis is figured in the original description, and has priority, it 

 certainly ought to be used. This species lives in Polyporus betulinus, 

 the common shelf fungus growing on white birch (Betula populifolia 



