STRUCTURE AND DEVELOPMENT OF EMBIA TEXANA. 



known, destitute of species. The Embiidae are therefore seen to 

 be tropicopolitan and also seacoast species, extending only a few 

 hundred miles into the interior along the principal water-courses. 

 In the warmer countries they appear at higher altitudes, in order 

 to preserve conditions of proper temperature and humidity. As 

 the species show a preference for palms and orchids, plants 

 which have a commercial importance, it is not surprising that 

 their distribution is artifically complicated. At least four species 

 have thus been taken in ship-yards and green-houses thousands 

 of miles from their native homes. Moreover, a natural maritime 

 distribution is quite possible on tree-trunks swept down some 

 river during flood-time and then carried about by ocean currents. 

 Texana has actually been found under the bark of a fallen tree lying 

 on a flood-plain. The next heavy rain would have carried that 

 tree-trunk down the Colorado River and ultimately to the Gulf of 

 Mexico. These facts should be remembered when we consider 

 the wide distribution of Saundcrsii. It might be mentioned that 

 like so many other introduced animals this species has become 

 exceedingly abundant in some places, even to a source of annoy- 

 ance in the island of Ascension. Insitlaris, too, is said to be 

 common on the sea-shore, every stone serving to shelter two or 

 three. This fact might indicate an introduction during times not 

 distant, with conditions favorable for a rapid increase in numbers, 

 and only recently an extension into the interior. 



That the Embiidae form an ancient group is undisputed. 

 Their uniformity of structure, so marked that characters of spe- 

 cific importance are few, shows that they have long passed the 

 zenith of their evolution. The variability of the antennae and of 

 the cerci, and even of the neuration of the wings might suggest 

 a decadence of these organs. The fact that the males are dimor- 

 phic and have only partially the need for wings, retaining them 

 possibly only to prevent too close interbreeding, while the females 

 are all wingless, also would lead us to that conclusion. But the 

 Embiidae have existed a long time in this dimorphic condition of 

 the male, for the wingless form is known in amber from the Ter- 

 tiary. This family of frail insects, one of the first of the twigs of 

 the great Orthopteran branch, seems certainly in process of ex- 

 tinction, but like other groups which were conservative in special- 



