234 i{. I. rococK. 



resemhles that of the Ainblypygi in geiieval form ami in man}' 

 structural details. In Ephebopns itiurinus and other 

 mygalomorplions spiders of the family Aviculariidte it is a 

 long'itudinally oval imperforated plate, with large anterior 

 cornna bounding the pharyngeal notch. The u]iper side is 

 furnished with four pairs of dorsally directed tendinous 

 processes, arising, as in I'hrynus, from a common ridge. 

 Below this the edge of the plate runs out externally into angular 

 processes which afford attachment to some muscles of the 

 legs. From the underside four pairs of processes pass down- 

 wards to meet the sternum ; tiie first pair arising from the 

 anterior cornua and running to the bases of the appendages 

 of the second pair, immediately behind the prosternum ; the 

 second, third, and fourth radiating from a common median 

 excre.scence, behind the pharyngeal notch, and reaching the 

 sternum opposite the third, fourth, and fifth appendages. 

 Remnants of a similar apophysis corresponding to the sixth 

 appendage, but failing to reach the sternum, are traceable 

 near the posterior end of the entosternite. The chief 

 difference between this entosternite and that of the Ambly- 

 pygi lies in the presence of the ventral apophyses corre- 

 sponding to the four posterior pairs of prosomatic apjiend- 

 ages. 



The figure of the entosternite of a Mygale given by 

 Bernard (3, figs. 3 and 5), and taken from a specinu'u in 

 the College of Surgeons' Museum, is diagrammatic. It is to 

 be noticed, however, that the ventral processes of the first 

 pair arc correctly represented as fused in the middle* line. 

 'I'he cntosternites of the species examined by Lankester (5, 6)^ 

 and Wasmann (11) agree closely with that of Ephebopus 

 m uriu us. 



In the great majority of the Mygalomorjiha^ the ento- 

 stei'uite is in the main like that of Kphebopu s, retaining 

 the four doisal and the four ventral apophyses, the ])oints 

 of attachment of the latter being visible on the external 



' In tlu' (ii,'uro |)iil)lisli((l in the second of llic two works enununatecl above 

 the dorsal side is l)j an oversiglit re|)resentcd as ilie ventral, and vice versa. 



