Mr. J. Blackwall on the Falces and Maxilla of Bpidei^s. 259 



lid(Bf belonging to different genera, from which I obtained the 

 following results : — In no instance was any appearance of a ridge 

 provided with a series of minute close-set spines observed near 

 the extremity of the outer margin of the maxillse; but Mygale 

 ursina and Cteniza nidulans were found to have that deficiency 

 amply compensated by short, distinct, black spines, grouped, 

 apparently without order, on the inferior surface of the base of 

 those organs, towards their inner margin, and to have the apex 

 of the lip also provided with similar spines ; Mygale zebra has 

 spines at the base of the maxillse^ but none at the extremity of 

 the lip; and Atypus Sulzeri, which has the palpi inserted near 

 the base of the maxillse, on the outer side, is provided with nu- 

 merous short spines on the inferior surface of those organs, to- 

 wards the inner margin, but is without any either at their base 

 or at the apex of the lip. 



I have hesitated to apply the term teeth to the conspicuous 

 spines at the base and towards the inner margin of the inferior 

 surface of the maxillse and at the apex of the lip of certain spe- 

 cies of the family Mygalidce, notwithstanding that they are 

 employed by them in retaining and also, to some extent, in 

 lacerating their prey; but to a remarkable group of spines, 

 situated on the superior surface of the maxillse of Mygale zebra, 

 and clearly indicating, by its position and structure, that the 

 principal function it performs must be that of mastication, the 

 appellation of teeth appears to be more appropriate. The 

 spines composing this group, which are of a dark-brown co- 

 lour, and have their pointed extremity directed towards the 

 inner margin of the maxillse, are fewer in number, enlarged at 

 the extremity, and much longer and more distinct near the 

 posterior end of each group than the closely compacted ones 

 that form its anterior part. These spines, by their figure and 

 arrangement, present a highly interesting subject for inspection 

 under the microscope. 



From the foregoing observations it is evident that much careful 

 investigation is yet required to complete our knowledge of the 

 various minute appendages connected with the external organs 

 of spiders and of the purposes to which they are subservient. 



EXPLANATION OF PLATE X. figs. 1-3. 



Vig. 1. The left maxilla and palpus of Mygale ursina, magnified: a, the 



spines at the base of the former. 

 Fig. 2. The lip of Mygale ursina, magnified : h, the spines at its apex. 

 Fig. 3. The right maxilla and palpus of Mygale zebra, magnified : c, the 



spines on the superior surface of the former. 



