BREED: METAMORPHOSIS OF THE MUSCLES OF A BEETLE. 327 
(Plate 1, Figure 3, ext.al. pa. mtthx.) of two fibres, which extend from 
the posterior lateral surface of the metathorax ventrally, and a little 
toward the median plane to attach to the posterior edge of the 
leg, very close to the attachment of the second flexor of the coxa. At 
this stage its only function is that of flexor of the coxa. In the pupa 
(Plate 2, Figure 5, ext. al. pa. mt’thx.) a fusion of the two fibres takes 
place, and a very considerable shifting of position. The attachments of 
this muscle in the zmago (Plate 4, Figure 9, ext. al. pa. mt’thx.) are, dor- 
sally, to the small cupule, which is placed immediately posterior to the 
large cupule, and, ventrally, to the ventral surface of the coxa just lateral 
to the insertion of the second flexor of the coxa. 
Relaxator extensoris alae of Luks. 
(Releveur de la grande cupule of Straus-Diirckheim ; dorso-préaaillatre 
of Amans.) 
There is some doubt as to the larval condition of this muscle and the 
few muscles next described ; this is due principally to their small size. 
During pupal life, this muscle and the relaxator alae metathoracis are so 
closely united as to be indistinguishable. In fact, there is little more 
than a mass of tissue containing remains of larval muscle and having 
about the position indicated in Figure 5 (Plate 2) by riz. eat. al. and 
rlx. al. mt’the. Out of this mass are differentiated the two muscles men- 
tioned above. In the 7mago the relaxator extensoris alae (Plate 4, Figure 9, 
riz. ext. al.) is inserted on the edge of the large cupule to which the 
extensor alae magnus metathoracis is attached. Its origin lies almost 
directly dorsal to this point on the wing-bearing apophysis. 
Relaxator alae metathoracis of Luks. 
(Relaxateur de Vaile of Straus-Dirckheim ; muscles du tampon of Amans.) 
The attachments of this muscle in the zmago (Plate 4, Figure 9, riz. 
al. mt’thx.) are as follows. Its origin is on a small cupule placed near 
the dorsal attachment of the musculus lateralis metathoracis anterior 
(Plate 5, Figure 11, 7. mé’tha. a.), from which it extends laterally, and 
somewhat ventrally, to attach on the base of the wing. 
As to the larval condition of the two muscles last described (77a. eat. 
al., rlz. al. mt’thx.), it seems probable that they are derived from three 
fibres. It is possible, and even probable, that the two fibres so marked 
(Plate 1, Figure 4, riz. ext. al. ?) give rise to the relaxator extensoris 
alae of the imago, and that the other fibre (Plate 1, Figure 4, riz. al. 
