2(J Journal New York Entomological Society. [^'°'- xxiv, 



18. The leaping- habit appears in the most diverse Arthropods {e. 

 g., Arachnids, Talitridse and other Crustacea, etc.) and may indicate 

 a stem tendency in a group which also exhibits the tendency to the 

 formation of paranotal expansions. 



19. It is possible for certain forms closely allied to the Insecta 

 (such as the Crustacea) to develop the power of gliding through the 

 air for several rods, thus making it more readily comprehensible 

 that insects could have developed the power of a gliding " flight " in 

 a somewhat similar fashion. 



Worcester (1914) observed the '"flight" of such a Crustacean, 

 while boating near the coast of Palavan, at the edge of the shoal off 

 East Island (in the Philippines), and describes the creature as fol- 

 lows : " It looked more like a crayfish or shrimp with one or two 

 pairs of much flattened legs directed forward and others curving 

 backward, the legs and the lobes of the tail making the supporting 

 planes ... it was unquestionably a very transparent crustacean from 

 fifteen to twenty centimeters in length . . . and there remains no 

 doubt of the existence in the Philippines of a marine crustacean from 

 fifteen to twenty-five centimeters in length, which has the power of 

 rising rapidly from the water and flying after the fashion of a flying 

 fish, for several rods." The specimens observed invariably rose 

 against the wind. 



We know of no parallel case in which tracheal gills have been 

 used as gliding organs ! 



20. If ontogeny in a measure recapitulates phylogeny, the form- 

 ing wings of the lower pterygote insects should pass through a para- 

 notal stage, if the wings were derived from paranota — and conversely, 

 if they were derived from tracheal gills, they should pass through a 

 stage comparable to tracheal gills. If we observe the forming wings 

 of the most primitive winged insects, such as the Plecoptera (Fig. 18, 

 Plate II) or the Blattids and Mantids (Fig. 9, Plate II) it is clearly 

 evident that the upper surface, at least, of the wings arise as paranotal 

 expansions of the tergum, rather than as tracheal gills ! Further- 

 more, since the wings of all insects must have had a common origin 

 (as was brought out in the previous discussions) the wings of insects 

 with a complete metamorphosis should show traces of a tergal origin, 

 and this Heymons, 1896, has shown to be the case in the beetle 

 Tenehrio. 



