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SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 1 37 



On the metatergum (MtT) there is only one median desclerotized 

 area, which in size and shape varies somewhat in different individuals. 

 This area is generally shaped like an inverted V and, as has been 

 already stated, tends to be smaller in the short-winged form. The 

 lateral desclerotized areas figured by Snodgrass (1929) in the meta- 

 tergum of Dissosteira do not exist in Marellia, which in this detail is 

 similar to the corresponding region of Nomadacris septem fas data as 

 figured by Albrecht (1956). 



The pterothoracic pleura. — The pleural region of the pterothorax 

 of Marellia remipes (fig. 8) is similar to that of Dissosteira (Snod- 



Tr 1 



Fig. 6. — Prothorax of Marellia remipes, lateral view. 



Cx, coxa of prothoracic leg ; Eps, episternum ; T, protergum ; Tn, trochantin ; 



Tr, trochanter. 



grass, loc. cit.). A remarkable feature, however, is the greater de- 

 velopment of the mesothoracic spiracle {Spo) in Marellia, and the 

 hairy covering of the prepectus and adjoining membrane in its vicinity. 

 Considering that this anterior part of the mesothoracic pleural region 

 is covered by the posterior edge of the lateral lobe of the pronotum, 

 it seems highly probable that the mesothoracic spiracle is functional in 

 subaquatic respiration. The hairs on the lateral regions of the pre- 

 pectus are probably a hydro fugous device for the retaining of air 

 bubbles when the insect is under water, serving as a respiratory sup- 

 ply. As we shall see below, the first and second abdominal spiracles 

 are probably functional too in the submerged insect. 



The pterothoracic sterna. — The united sternal plates of the meso- 

 thorax and metathorax form the broad ventral surface of the ptero- 



