THE FIRST LEG SEGMENTS IN THE CRUS- 

 TACEA MALACOSTRACA AND 

 THE INSECTS 



By F. CARPENTIER AND J. BARLET 



Laboratory of Invertebrate Morphology 

 University of Liige, Belgium 



INTRODUCTION 



One of the great services Dr. R. E. Snodgrass has rendered to our 

 science is to have pointed out in several of his recent v^orks the lack 

 of coherence still prevailing between the data of insect morphologists 

 and those of specialists in other classes of Arthropoda. In his fine 

 treatise of 1952 (pp. 284-285), for instance, he observes that one does 

 not know what can correspond in the inferior classes of Arthropoda 

 to those sclerites at the leg bases that we have studied so thoroughly 

 in the Apterygota. 



We preferred not to try to settle this question before acquiring a 

 sufficient knowledge of the said formations in the Apterygota them- 

 selves. Their diversity within this subclass is so great that what they 

 can have in common remained unknown for a long time. Hard work 

 was needed to make up for this lack of knowledge and to enable us 

 to show within the limb base new guiding marks in which we only 

 now have taken interest, namely, the ties of the endosternites. These 

 are more or less numerous according to the morphological types under 

 examination ; a great deal of experience was necessary to distinguish 

 and recognize them in the various types. 



As our attempts proved convincing, we set about gathering the ele- 

 ments of an answer to the question raised by our eminent American 

 colleague. The Myriapoda ^ gave us little useful information ; their su- 

 pracoxal structures are too specialized. The Crustacea Malacostraca 

 turned out to be of far greater interest in this connection, and we have 

 already published a short paper ^ on them. We are pleased to offer 

 in the present article, as a tribute to R. E. Snodgrass, more complete 

 explanations and some illustrations on the same subject. 



It is known that we have observed in quite varied types of Aptery- 

 gota the presence of two main overlying supracoxal zones : the ana- 



"^ Sculigera, Lithobius, Cryptops, Scolopendra (unpublished observations). 

 2 Proc. loth Internal. Congr. Ent., Montreal, 1956, vol. i, pp. 489-490, 1958. 



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