gn the Species of Trap-door Spiders. 177 



maxillae, and between it and the base of the cheliceras I observed 

 a minute oblong deflexed tontruelet of a membranous texture, 

 which seems analogous to the hypopharynx of insects ; it is of a 

 membranous texture, and was observed without dissection or the 

 slightest difficulty. I presume this is the part wliich Latreille 

 names the camerostome. It is impossible on examining the loco- 

 motive appendages of this insect not to be struck witli the con- 

 viction that the maxillae are but a modified pair of feet. If we 

 examine the hind pair of feet, for instance, we find a sliort piece 

 articulating with the sternum, which is analogous to the coxa of 

 insects ; this is succeeded by a still smaller piece, which is as 

 evidently the troch^mter ; then comes the most powerful joint 

 of the foot, which is the femur ; then is there anotiier short joint 

 which seems to constitute, with the following, the tibia ; and these 

 are followed by on apparently two-jointed tarsus, thus making 

 seven joints in the foot, the number ordinarily assigned to the 

 legs of the Arachnlda. In the system of M. Savigny the names 

 given to these joints are as follows : — 



of the feet of 

 lasecta. 



J . —La hanche = the Coxa 



2. — Laexinguinal } ... ( the Trochanter 



r, T f. ° , ; composino; la cuisse = > .l c- 



3. — Le femoral ..S '^ ( the rerour .... 



4. — Le genual . . i • i • t, S .i t i • 



c T fu- I I composing la jambe = J Uie libia .... 



6. — Le melalarse > • i ■ i V .u t 



7.— Le tarse \ composing le pied = ^ the Tarsus .... 



Now the maxillae and their palpi, as indeed Savigny has long ago 

 shown, are but a pair of modified legs. If we therefore consider 

 the maxilla as the basal joints or the coxae of a fore foot, we shall 

 find that the first and the four following joints of the palpi cor- 

 respond, joint for joint, with the same joints of the foot, in extent 

 of development. The difference takes place in the palpi having 

 a joint less at the end than the feet; by connparing, however, 

 the palpus and the first foot of this insect, it is quite evident that 

 the last joint of the palpus is composed of the two terminal joints 

 of the foot soldered together. 



We thus arrive at the following coirespondence between the 

 joints of these two members : — 



FEET. I'.4LPUS. 



Coxa, or La hanche, Sav. ■ ■ Maxilla. 



Trochanter, or . < L'exinguinal, Sav. , . 1st joint (.Article sous axillaire, Sav.) 



Femur, or Le feinoial, .iiii. . . 2n'l joint (iiunuTal, Sav. ) 



1st joint of the Tibia . . Le genual, Suv. ..3id joint ((^ibilal, Sav ) 



2nd joint of the Tibia . .Le tibial, Sav 4th joint (Radial, Sav.) 



]st } joints of the S Le metatarsc, i'lfi. ) -,, • , ,,^- ■.-,(. ^ 

 ' J J J ,,, . J I , I. loth oint (Digital, .but.) 



2na J laisi ( LetJise, 6'n. ..S \ o > / 



