BREED: METAMORPHOSIS OF THE MUSCLES OF A BEETLE. 323 
the imago, are misnomers when applied to the muscle in its larval state. 
Even though such misnomers may cause confusion, they are retained in 
this paper because no better nomenclature is available at present. 
In the detailed description of the muscles, the order followed is: 
(1) dorsal antero-posterior, (2) lateral dorso-ventral, and (3) ventral 
antero-posterior. By this arrangement, the wing muscles of the imago, 
both direct and indirect, are spoken of first. 
(1) The dorsal antero-posterior group of muscles is shown in Figure 1 
(Plate 1), which is a view of the left side of the Jarval metathorax seen 
from above (dorsal), anterior being up on the plate. Figure 2 is a 
similar view of the pupal metathorax. In the upper portions of Figure 9 
(Plate 4) and Figure 11 (Plate 5) is shown the same group of muscles 
in the imago as they would appear when seen from the left side of the 
thorax, after cutting away the lateral wall of the metathorax. 
Musculus metanoti of Luks. 
(Abaisseur de Vaile of Straus-Diirckheim ; dorsal of Amans.) 
The musculus metanoti is one of the most important of the indirect 
wing muscles, since it functions as the principal depressor of the wing 
in the imago. In the larva (Plate 1, Figure 1, mé’nt.) it exists as three 
distinct muscles, extending from the anterior to the posterior boundary of 
the metathorax. At this stage the three muscles do not even lie parallel 
toone another. It is their subsequent history only which shows that they 
constitute one imaginal muscle. Just before pupation, in a larva which 
is no longer feeding, these three muscles show histological evidences of 
metamorphosis, which will be described later. There is very little 
change anatomically, till pupation, when there is a quite rapid shifting 
of the attachments of the three muscles, caused by the unequal growth of 
the hypodermis. In the pupa (Figure 2, mt’nt.) they still extend 
throughout the entire length of the somite, but have changed their rela- 
tive positions so that now they lie parallel to one another. In the older 
pupa they grow in size until they touch each other, and in the young 
amago (Plate 4, Figure 9; Plate 5, Figure 11, m#’nt.) they become so 
united as to be almost indistinguishable. Each of the three original 
muscles has divided lengthwise into from three to nine fibres, so that the 
entire adult muscle is composed of about fifteen fibres. 
During pupal life there is formed an ingrowth of the hypodermis 
along the dorsal portion of the suture between the meso- and metathorax, 
and from this is formed the mesophragma of the imago (Plate 4, Figure 9, 
