112 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I37 



region d of the endosternite adheres and which must be anapleural.^® 

 There are two inferior arms of the endosternite of Anaspides: 

 f and e. The arm / thus exists, but no furcal apophysis developed 

 within it. Our figures 6 and 7 show that in Anaspides as well as in 

 Penaeus the crural nerve en passes between / and e. One will at once 

 object that in the Apterygota the crural nerve is not posterior to / 

 but anterior. This difficulty at first embarrassed us, but later we found 

 that the crural nerve can be connected with the ganglion by two roots, 

 one anterior to / (or fii), the other posterior. The two roots coexist 

 in Anialo penaeus, but quite often only the posterior root exists in the 

 Crustacea. In the insects it seems that it is always the anterior one.^^ 

 Thus our difficulty was only apparent. 



We see that in spite of the difference of aspect and of composition 

 of the endosternites of Anaspides and of Penaeus we have been led 

 to locate in both crustaceans the homologues of the main lateral and 

 inferior arms of the Apterygota. 



CONCLUSIONS CONCERNING THE LEG BASE AND THE 

 PLEURON OF THE MALACOSTRACA 



We have presented in this paper a comparative analysis of these 

 parts of the body only in two Malacostraca : that regarded as the most 

 "primitive" of all and a decapod particularly "primitive" too. We 

 have made a few references to other species which have also been 

 studied. Our present knowledge of the Malacostraca may seem insuffi- 

 cient, but one should bear in mind that our study has dealt with only 

 a very limited region of the body of the Crustacea and that this same 

 region had been previously studied for many years with the greatest 

 care and with exactly the same method on various Apterygota and 

 even (unpublished) on Myriapoda. The experience so acquired will 

 have kept us, let us hope, from making identifications based upon 

 coincidences rather than upon a real morphological kinship. 



At any rate one result of our researches seems to be beyond all 

 question : the true pleural region of a malacostracon cannot contain 



28 In the first of our works on the Apterygota (Carpentier, 1946, p. 177) we 

 indicated that this sclerite is "very ambiguous," but we thought that we could 

 refer it to the catapleuron. The preoccupation to classify the propleural sclerites 

 of the Machilidae according to two circles led to this interpretation, which 

 seemed to be supported by certain features of Thcrmobia (Lepismatidae). How- 

 ever, it must be false as we found out later in our studies. 



-^ Constant, too, in the Pterygota. One would not think so upon examining 

 fig. 2 in Josting's work (1942) concerning Tenebrio; but we were able to show 

 that his figure is in error. 



