hearing upon the Classification of Spiders. 307 



two smaller auxiliary pairs, an anterior and a posterior, each 

 corresponding to one of the larger mammillae, and differing from 

 it in consisting of a single, straight, subcylindrical segment, the 

 principal mammillae being broad at the base, pointed distally, 

 and crescentically curved. Thus there are in all no less than 

 eight mammillae constituting the external spinning-apparatus, 

 although the two internal pairs appear to be functionless so 

 far as the emission of silk is concerned (fig. 1). 



The upper surface of the abdomen is provided with nine * 

 chitinous tergites, the anterior of which are large and over- 

 lapping, the posterior small and widely separated. The 

 anterior two are represented on the ventral surface by two 

 large sternal plates, the anterior of which covers the aperture 

 of the generative organs and those of the front pair of pulmo- 

 nary sacs, the posterior similarly covering the hinder pulmo- 

 nary sacs. 



The cephalothoracic sternum is extremely narrow, its 

 width being about one third of its length ; the carapace, on 

 the other liand, is remarkably wide and flat and the coxfe of 

 the ambulatory appendages, compensating for the narrowness 

 of the sternum, are very long. In the British Museum 

 example, moreover, tlie labium is very short and wide, much 

 wider in fact than the sternum, its great width being due to 

 the prolongation of its lateral borders beneath the cox£e of the 

 second pair of appendages, so that these segments (the 

 maxillaj) are in front of the labium, as in Hypochilus. 



The basal segments of the mandibles are directed forwards, 

 as in the Territelariae, the plane of their articulation with the 

 cephalothorax being vertical or nearly so with respect to the 

 long axis of the body ; but their inner surfaces are not flat- 

 tened and contiguous to the same extent as in the Territe- 

 larite, their distal extremities diverging so that there is a 

 considerable interval between the bases of the fangs ; these 

 fangs consequently when closed lie obliquely inwards and 

 backwards, and not directly backwards as in the Territe- 

 lariaj. 



In the presence of chitinous plates on the upper surface of 

 the abdomen and of two sternal plates on the anterior extre- 

 mity of its under surface, in the extreme narrowness of the 

 sternum, but above all in the position and structure of its 

 spinning-mammillge, Liphistius differs from all known spiders ; 

 and no gradational forms are known which would lessen the 



* Teste Schiiidte. In the British Museum example tlie lutej^umeut at 

 the posterior end of the upper surface of the abdomeu has boeu destroyed, 

 so that of my own knowledge I cannot speak as to the exact number of 

 these plates. Seven, however, are clearly visible. 



21* 



