594 ORDER APODA. 



be seen from the outside. Each separate ribbon expands 

 a little at its two ends, which are attached to the articula- 

 tions separating the successive segments : I carefully ob- 

 served that they did not pass over at either end to the 

 adjoining segments : hence their action must be either simply 

 to shorten and arch each segment separately; or when acting 

 together, to shorten the whole body, or perhaps the ventral 

 or dorsal surface by itself. 



In the first segment, and in the three posterior segments, 

 these longitudinal muscles alone occur ; but on the seven 

 segments, from the second to the eighth inclusive, there are 

 other oblique latero- ventral muscles. These muscles lie 

 within the longitudinal muscles, and adhere pretty firmly to 

 the coat (e, e, fig. 7) of the great ovarian sack. At their ventral 

 extremities they are attached, near the anterior margin of 

 each segment, beneath the point of attachment of the longi- 

 tudinal fasciae, and thence they run posteriorly in an oblique 

 line to the anterior margin of the next succeeding segment, 

 where they are attached : so that these muscles run obliquely 

 from segment to segment. The first of these oblique muscles, 

 lying chiefly within the second segment of the body, is thinner 

 and longer than the others : those within the third and fourth 

 segments are short : those within the fifth and succeeding 

 segments extend, at their dorsal (or lower in fig. 7) extremi- 

 ties, as far as the outer dorsal longitudinal fasciae : those 

 within the seventh segment are broad and short, and cross 

 the longitudinal muscles at only a small angle. In the 

 eighth segment, there is an oblique lateral muscle, like 

 that in the seventh segment, running from the ventral sur- 

 face towards the dorsal surface ; but there is in addition a 

 second oblique lateral muscle, rising from the dorsal surface, 

 and running towards the ventral surface. This muscle does 

 not occur in the other segments, but in the fourth segment, 

 at the dorsal end of the oblique latero-ventral muscle, there 

 may be seen a small branch of fibres, at right angles, which 

 seems to represent a muscle homologous with that just men- 

 tioned in the eighth segment : obscure traces, moreover, of 

 similar fibres, can be detected in some of the other seg- 

 ments : had these oblique latero-dorsal muscles been as fully 

 developed in the seven anterior segments of the body, as on 



