014 TEXT-ROOK OF ENTOMOLOGY 



We will copy the summary of Newport, who adopted the nomenclature applied 

 to these parts by Burmeister : 



"The muscles that connect the head with the thorax are contained within 

 the prothorax (Fig. 232, 2), and are of three kinds, extensors, flexors, and 

 retractors. The extensors, levatures capitis (a, a), consist of two pairs, one of 

 which arises from the middle line of the pronotum, and diverging laterally from 

 its fellow of the opposite side, passes directly forwards, and is inserted by a 

 narrow tendon into the anterior superior margin of the occipital foramen. The 

 other arises further back from the prophragma. It is a long, narrow muscle 

 that passes directly forwards through the prothorax, and is inserted by a tendon 

 near the superior median line of the foramen ; so that, while this muscle and its 

 fellow of the opposite side elevate the head almost in a straight line, the one first 

 described, when acting alone or singly, draws the head a little on one side ; but 

 when the whole of these muscles act in unison, they simply elevate the head 

 upon the prothorax. The depressors or flexors, depressores capitis (6), are 

 exceedingly short muscles, which arise from the jugular plate, or, when that 

 part does not exist, from the border of the prostermnn, anil are attached to the 

 inferior margin of the occipital foramen. They simply flex the head on the pro- 

 thorax. The lateral flexors, (pressures externi (d), are two little muscles that 

 arise from the same point as the preceding, and are attached to the lateral inferior 

 margin of the occipital foramen. The rotatory muscles, rotatores capitis (<) 

 are two flat muscles like the elevators, which arise, one at the side of the ante- 

 furca and the other from the posterior jugular plate, and passing upwards and 

 outwards are attached to the lateral margin of the occipital foramen. The 

 retractor or flexor of the jugular plate is a small muscle (e) that arises from the 

 margin of the antefurca, and passing directly forwards is inserted by a small 

 tendon into the middle of the jugular piece. The oblique extensor of the jugular 

 plate is a long, slender muscle (/) that arises from the external margin of the 

 pronotum, and passing obliquely downwards and forwards traverses the pro- 

 thorax and is inserted by a narrow tendon to the jugular plate immediately before 

 the retractor. The other retractor (a) arises from the anterior superior bound- 

 ary of the pronotum, and passing downwards is inserted into the jugular plate 

 between the larger levator and flexor capitis. 



"The muscles proper to the prothorax consist of four pairs, by which it is 

 united to the succeeding segments. The first of these, the superior retractor, 

 retractor prothoracis superior (/i), arises by a broad, fleshy head from the 

 anterior external margin of the pronotum, and passing directly backwards is 

 inserted by a tendon into the prophragma, a little on one side of the median line. 

 The next muscle of importance, the inferior retractor (i), arises from the anterior 

 border of the medifurca, and is united to the posterior of the antefurca, thus 

 forming with that muscle part of the great recti of the larva. This muscle must 

 be considered as the proper depressor of the prothorax. The elevator prothoracis 

 (A:) is narrow, pyramidal, and arises fleshy from the lateral surface of the 

 prophragma. It passes downwards and is attached by a narrow tendon to the 

 superior portion of the antefurca. The rotatores prothoracis are the largest of 

 all the muscles of this segment. They arise, one on each side (Z), by a narrow 

 head from the posterior part of the pronotum, and passing beneath the pro- 

 phragma are considerably enlarged and attached to the tegument between the 

 two segments, and also to the anterior portion of the mesothorax. The remain- 

 ing muscle proper to the prothorax is the closer of the spiracle, an exceedingly 

 small muscle not shown in the drawing. 



" The other muscles of this segment are those of the legs, which are of consid- 

 erable size. There are three distinct flexors of the coxa (m, n, o). The first of 



