398 ARABELLA TRICOLOR. 



larger. The plate in front has the same number of teeth, but the anterior far surpasses 

 the rest in size. The small anterior tooth has a single large curved fang. The mandibles 

 (Plate LXII, fig. 8 c) are cleaver-shaped, black, with a pale tip which forms an oblique 

 cutting edge sloping outward from the point of attachment. The body of each process is 

 long, and the short and narrow posterior process commences after an abrupt shelf. 



In transverse section (Fig. 81) the cuticle is dense, and the hypoderm proportion- 

 ally well developed. The longitudinal muscles are massive, the dorsal exceeding the 

 ventral in size, only a chink separating them in the mid-dorsal line, and the dorsal vessel 

 is thus (in contraction) pushed far inward. The oblique muscles are powerful, and are 

 attached to the upper and outer border of the nerve-area, the vertical bands from the 

 alimentary canal being inserted at the same points. The nerve-area has a long pedicle 

 furnished with many blood-vessels, and in contraction is somewhat ovoid, no neural canal 

 being visible. 



The first foot (Plate LXXIV, fig. 5) is of considerable size, and consists of a small 

 dorsal lobe above the setigerous process, and a large lower lobe (posterior and tongue- 

 shaped in lateral view) which has a slight slant backward. The row of bristles in this 

 foot is less oblique than in the subsequent feet, being situated between the dorsal cirrus 

 or lobe above and the large ventral lobe beneath. At the tenth foot (Plate LXXIV, 

 fig. 5 a) the bristle-row passes from above downward and forward below the upper lobe, 

 and in front of the posterior lobe. This arrangement continues throughout the greater 

 part of the body, only posteriorly at the tail the line of the bristles is somewhat less 

 oblique, and the spinigerous lobe more prominent. The tenth foot has only bristles of 

 one kind, viz., tapering winged bristles, and while the dorsal lobe or cirrus is of consider- 

 able size the large posterior lobe is less than it becomes in the succeeding feet. The 

 points of many of the developing bristles project from the foot at the base of the 

 long bristles, which appear to be brittle. The bristles (Plate LXXXIII, figs. 2 and 2 a) 

 are of two kinds, (1) a dorsal series with a gentle curve and rather long, finely tapered 

 tips with narrow wings, and (2) a series with shorter tips which have a more abrupt 

 curve at the end of the shaft, the wings opposite the curve being expanded and provided 

 with about five serrations. 



The foot has from five to seven spines anteriorly, and by-and-by the dorsal region 

 has a group of small spines which go to the base of the cirrus. In the posterior feet this 

 dorsal group of spines is considerably larger, though they do not attain the size of the 

 inferior series. There are four or five in the upper group. 



The foot in the middle of the body (Plate LXXIV, fig. 5 b) diverges little from the 

 tenth, except in the form of the dorsal cirrus, which becomes a mere papilla. The long 

 posterior lobe curves upward behind the setigerous process, but is not longer than in 

 front. The hypodermic cells are regularly arranged, and the whole process is highly 

 vascular. 



The posterior feet (Plate LXXIV, fig. 5 c), again, present a dorsal cirrus somewhat 

 smaller and more tapered than in front, whilst the curved posterior lobe is slightly 

 shorter than in the middle of the body. 



The feet continue prominent, though the body tapers to the tail, two or three imme- 

 diately in front of the pygidium being minute. Dorsally over the vent are two cirri, 



