244 Mr. A. Tulk on the Anatomy of Phalangium Opilio. 



rating tliem carefully at their articulations^ the muscular fibre is 

 observed to be continued from one to the other, as far as the 

 distal end of the second portion of the tibia, where two long and 

 delicate tendons are given off, which traverse the entire series of 

 tarsal joints, running along their under surface. The chief 

 muscles of the chelicerae and palpi consist of an elevator and de- 

 pressor for each of these organs, the latter being somewhat the 

 larger of the two. The remaining fasciculi, connected with the 

 other organs of manducation, are too minute to admit of any 

 satisfactory demonstration. PL III. fig. 13. * *, however, repre- 

 sents a pair of these, attached to the margins of the second pair 

 of jaws. The other muscles of Phalanyium, as connected with 

 the performance of some special functions, will be considered in 

 speaking of those structures of which they form a part. I have 

 already alluded to the probable use of the longitudinal and oblique 

 fibres of the corium, that they may serve, in other words, to di- 

 minish the bulk of the animal's body, more especially that of the 

 abdominal cavity, which must be necessary to aid in the expul- 

 sion of the feeces, the extrusion of the ova, or of the external ge- 

 nerative apparatus in both sexes. 



Organs of Nutrition. — Like the alimentary canal of the true 

 Spiders and of the Scorpionidce, that of the Phalangia consists of 

 a straight intestine passing from one extremity of the body to the 

 other, but which, instead of being more or less narrow, as in 

 them, throughout its entire course, dilates within the abdominal 

 cavity, to form a wide and capacious sac, occupying nearly its 

 whole breadth. It commences in front by a mcmbrano-coriaceous 

 pharynx (PI. IV. fig. 1^. ph), which opens externally, between 

 the first and second pair of maxillse, and is lodged within the con- 

 cave structure, described above as the epipharynx [ex). Its upper 

 surface is curved, to adapt itself to the interior of the latter, and 

 presents in the middle an elongated horny plate (*), the anterior 

 half of which (PI. IV. fig. 16. dp) is narrow, deflexed, and con- 

 stricted in front, towards the apex, where it terminates by form- 

 ing a corneous lip [1), which is opposed to two others (/'/'), placed 

 laterally and beneath it, the three nearly meeting, so as to leave 

 a narrow and somewhat triradiate opening into the pharynx su- 

 periorly, while below them the latter expands into a wide trans- 

 verse aperture (a). It was probably an imperfect view of the 

 above lips, which appear but as dark spots when seen under a 

 low power, that led Savigny f to admit the existence of two, and 

 subsequently three pharyngeal orifices in the Phalangia. The 

 posterior moiety of this plate is emarginate behind and nearly 

 three times the width of the preceding one, and deeply grooved 



t Mem. sur les Aniin, sans vertebres: Paris, 1816. 



