CRUSTACEAN LEG SEGMENTS — CARPENTIER & BARLET lOI 



region of the thoracic segment in the shape of a rather reduced 

 "laterotergal plate." It would be, after all, a "pleuron," the aspect of 

 which would be quite different from that of a basal ring of the limb. 



The only typical precoxopodite that Snodgrass observed in the 

 arthropods in general is the "subcoxa" of Strigamia. This one com- 

 pletely encircles the coxa but remains a part of the body wall. Stri- 

 gamia is a geophilomorphous chilopod, an arthropod the whole organi- 

 zation of which is far "less primitive" than Anaspides. Hence 

 Snodgrass thinks (1952, p. 208) that, after all, there is no convincing 

 evidence for a theory according to which a subcoxa, or primitive 

 pleuron, would originally have made up the functional base of the limb 

 of the arthropods. 



However, we had to check whether the base of the maxilliped had 

 been correctly described and figured. Snodgrass's data do not fit in 

 very well with Hansen's (1925), and the results obtained by the latter 

 have not been discussed. There is nothing astonishing in the fact that 

 Snodgrass could not study with the same degree of care every detail 

 which comes up in so vast and extensive a work as his. But here a 

 greater accuracy is necessary. 



We thought that the first point to check in Anaspides was to which 

 segment of the limb the exopod is attached. Hansen regarded it as 

 pertaining to a very short basipodite. Snodgrass, who neglected this 

 last segment, saw the exopod attached, quite proximally, to the fol- 

 lowing segment, which is well developed and which Hansen named 

 preischiopodite. We found that Snodgrass was right. Our figure ic 

 shows that the exopod mainly pertains to a differentiated region at the 

 proximal end of the large segment of the leg. This "preischiopodite" 

 is thus the true basipodite. Besides it is quite usual for the exopod 

 of the thoracic limbs of the Malacostraca to pertain to the base of 

 the basipodite.^ These relations are the same as those we observed in 

 a general way in the Malacostraca we studied (see for instance 

 Penaeus, fig. 2). The exopod of the thoracic legs of Eupagnrus which 

 puzzled Hansen (1925, p. 143) and which we reexamined with care 

 is at least as proximal as that of Anaspides. Besides, the Danish writer 

 found that one could be tempted to refer it to the coxopodite as well 

 as to the following segment. 



Yet the reduced region of the maxilliped as well as of the legs of 

 Anaspides which Hansen regarded as a basipodite, remains for us 

 equivalent to a segment. This one is indeed very short, so short that 

 on the side toward the body of the crustacean one could see but a 



^ The "base" of a segment we define as its proximal end. 



