BREED: METAMORPHOSIS OF THE MUSCLES OF A BEETLE. 319 
based on dissections in which only imaginal forms have 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 other 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 (799). 
Of the three papers that deal with the imaginal muscular system of 
Coleoptera, the monumental work of Straus-Diirckheim (’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 Léveille (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 
