160 Mr. A. Tiilk on the Anatomy of Phalangium Opilio. 



joints are more slender and uniform throughout. I have exa- 

 mined with care the palpi of several male and female Phalangia, 

 and can discern no svich structure as that indicated by Hahn in 

 the male. The only apparent differences in these organs are^ a 

 gi-eater thickness of the joints in the male (PI. III. fig. 6. S ) 

 than in the female (PI. III. fig. 7. ? ), with the bristles upon 

 them stronger and better defined, and the anterior dilatation 

 of the terminal joint more abrupt and rounded in the former 

 than the latter. With regard to the chelicerse, the joints are also 

 larger and mor6 robust, and the posterior angle of the second 

 one is more prominent in the male than in the female (PI. III. 

 figs. 6, 7.). 



Posteriorly, and internal to the second joint of the palpi, are 

 situated the first pair of maxillce, a continuation, as has been seen 

 above, of their basal articulation (PI. III. fig. 3. A). When 

 viewed m situ from the under surface of the body (PL III. fig. 8. 

 A), they have the appearance of two membranous, dilated and 

 cordiform bodies, lying in contact with each other along the me- 

 dian line, their broad ends placed beneath the extremity of the 

 labrum (/), while their apices, directed towards the interval be- 

 tween the second pair of jaws, are marked by several cm'ved and 

 longitudinal folds. The turgid condition of these organs, and of 

 the succeeding pair, alluded to by Latreille* as occurring in them 

 when employed, seems in the present case to be caused by the 

 spirit, in which the specimens have been kept, penetrating and 

 distending their interior ; and this will be readily understood, 

 when it is premised that their, essential construction is that of a 

 coriaceous membrane, plicated and folded upon itself from below 

 upwards to form a hollow pouch. The form of these maxillae is 

 oblong, terminating in an irregular, slightly expanded, or clavate 

 extremity. They present for examination three distinct surfaces : 

 a superior, lying nearly upon a level with the upper part of the 

 epipharynx and labrum ; an inferior, directed obliquely upwards 

 and backwards ; and an internal, approximated with its fellow 

 along the median line. Upon the fii'st of these, posteriorly, and 

 to its outer side, is a conical curved projection (PI. III. fig. 9. k) 

 with an acute and membranous point ; and leading inwards from 

 the base of this, towards the apex of the labrum, with the sides 

 of which the jaws are united, is a thickened ridge (/). Beyond 

 the latter is the turgid dilatation of the maxilla, of a dark colour 

 towards the tip, from its becoming there densely clothed with 

 hair, and transversely plicated (m). Turning next to the inferior 

 sm-face (PL III. fig. 8. A), the shape of which, as resulting from 

 its being partly concealed by the second pair of jaws, has been 

 already described, by di-awing it slightly forwards, a dark, horny 

 » Op. cit. 



