106 Anopheles Maculipennis 
the dorsal integument in the prothoracic region on either side. This 
muscle passes downwards and outwards, and becomes attached to the 
ventral body wall, just external to the imaginal prothoracic leg-bud of 
its side. About the middle of the thorax a second series of such 
muscles are present; they consist of several bundles, widely separated 
from one another, which pass downwards and inwards to the sternal 
region. In the hinder part of the thorax a third series of tergo-sternal 
muscles are present; they pass almost vertically downwards on either 
side between the salivary glands and the cardiac coeca. 
The musculature of the thorax exhibits clear indications of an 
arrangement into three segments, and it is especially well seen in 
connection with the longitudinal sternal muscles. 
In the fully grown larva the developing imaginal thoracic muscles 
form very prominent objects; they are disposed in a longitudinal and 
a vertical series on either side of the body. They are very deeply 
staining and are in the form of short bundles in which are distributed 
great numbers of minute nuclei, but they do not exhibit any cross 
striation. The longitudinal series lie above the larval longitudinal 
tergal muscles and take the form of parallel cords situated on either 
side of the middle line. The vertical series are situated immediately 
external to the salivary glands, and are arranged in an anterior and a 
posterior group on each side. 
A number of muscles are also found in the neck, and their action 
brings about the remarkable rotatory movements of the head. The 
smaller of these muscles lie for the most part in the neck itself and 
pass in an oblique manner from one side to the other. There are, in 
addition, some much stouter muscles, which arise from the prothoracic 
region and pass up through the neck to be inserted into the base of 
the head. 
The musculature of the abdomen. In the abdomen there is no 
segmentally repeated system of tergo-sternal muscles, such as is present 
in many insects. The longitudinal muscles 1 , however, are very well 
developed and are much stouter than those of the thorax, and it is due 
to the action of these muscles that the larva performs its vigorous eel¬ 
like movements as it swims tail foremost through the water. The 
longitudinal tergal muscles are grouped together on either side of the 
dorsal vessel, and the sternal series have similar relations with the 
1 Grandpre and Charmoy remark (p. 33), <l Les principaux muscles sont les muscles 
longitudinaux et circulaires de l’abdomen”; this statement, however, is incorrect as there 
are no circular muscles present. 
