190 DE. C. CHILTON ON THE SUBTEREANEAN 



each has fine setae arranged on the surface near the base of the inner margin. The 

 outer margins appear thick and chitinous, but the rest of the lip is thin and delicate. 



The first maxilla (fig. 8) consists of two lobes, which appear somewhat indistinctly 

 articulated to a basal portion, whicli may perhaps represent the combined basos and 

 ischium, the two lobes representing the internal and external lacinice arising from the 

 basos and ischium respectively. See Boas [13, pp. 495-8] and Parker [84, p. 22]. 



There is a tuft of fine setae on the outer margin of the base near the articulation of 

 the outer lobe, and another on the inner margin at the base of the inner lobe. The outer 

 lobe is long, its articulation with the base very oblique ; the distal portion curves slightly 

 inward, having the mai'gins parallel and both fringed with numerous fine setae ; the end, 

 which is oblique, is crowned with numerous short spiniform setse, the innermost of which 

 are more or less denticulate. The inner lobe is narrow at the base, but expands some- 

 what toward the distal end ; it has both margins and a portion of the outer (posterior) 

 surface covered with rather long but very fine setae. At the rounded extremity there are 

 four long setae, rather distant from each other ; they appear segmented, and are densely 

 plumose and somewhat denticulated toward the extremity ; at the base of each of the 

 two innermost is a single simple seta. 



Bands of muscles can be seen attached to the bases of each of the lobes, but no muscles 

 extend into the lobes themselves, a fact which, without further evidence, would be almost 

 sufficient to show that the two lobes cannot represent the exopodite and endopodite of the 

 typical crustacean limb, as some authors have held. 



The second maxilla (fig. 9) is of the usual shape, and consists of a broad, somewhat 

 rectangular basal portion, having two lobes articulated to its distal end, and being pro- 

 duced distally on the inner side so as to form a third lobe, which, however, is not divided 

 off from the basal portion. The outer margin of the base is straight, and is fringed 

 almost throughout with numerous fine, stiff setae ; the inner margin is slightly concave, 

 and is fringed with two rows of setae. The outer (posterior) row consists of about 15 setae, 

 not very closely packed, and denticulate at the ends ; at the distal end of this row succeeds 

 a number of fi.ner stiff' setae, forming at first a kind of continuation of the row and then 

 spreading out so as to cover the surface of the end of the inner lobe. The inner (anterior) 

 row consists of a much greater number of setae, apparently simple, with thickened 

 bases, the setae being so closely packed . that the bases almost adjoin ; towards the 

 proximal end of the row the thickened base of each seta is rather long, but in the others 

 it o-radually decreases till in the setae at the distal end of the row the base is quite short. 

 This row of setae is situated along the edge of the inner margin ; but at the distal end, 

 when it has reached about halfway along the inner lobe, it leaves the margin and is 

 continued for a short distance along the inner (anterior) surface of the lobe ; beyond the 

 end of the row is a single simple seta. 



The inner lobe curves slightly inward ; its extremity is truncate, with the corners 

 rounded off, and it bears about 12 long setae, the outermost being the longest and 

 simply plumose, while the inner ones are shorter and in addition to the plumes bear 

 denticulations toward the ends, the denticulations increasing in distinctness and strength 

 as they proceed inward. 



