No tracheate Crustacea are known, but some terrestrial Isopoda develop pulmonary in-sinkings of the integument.
The oldest Tracheate actually known to bear spiracles is the Silurian Scorpion of Gothland and Scotland (Scudder, in Zittel’s Palæontologie, p.
The Caterpillar is not, as Harvey[190] maintained, a kind of walking egg; it is rather the primitive adult Tracheate modified in accordance with its own special needs.
We need not say that this is very far removed from the primitive Tracheate which morphological theory requires.
Palmén has proved, what is on other grounds clear enough, that stigmata are more ancient than tracheal gills, aerial tracheate respiration than aquatic.
It may be sexually immature, imperfect, destined to attain more elaborate development in a following stage, but it nevertheless marks the stage in which the remote Tracheate ancestor attained complete maturity.
The appearance of tracheae in place of lung-sacs cannot be regarded as a starting-point for a new line of descent comprising all the tracheate forms; tracheae seem to have developed independently in different lines of descent.
Probably tracheae have developed independently by the same process in several groups of tracheate Arachnids.
We are compelled to take a similar view of the agreement between the tracheal air-tubes of Arachnida and other tracheate Arthropods.
The development of the first Tracheate Insects out of gill-bearing Zoea-crabs, must have taken place between the end of the Silurian and the beginning of the coal period, that is, in the Devonian period.
For several reasons seem to support the supposition that the Gilled Arthropods have developed out of a branch of articulated worms, different from that which gave rise to the Tracheate Arthropods.
The present tracheal respiration of the Tracheata developed at a later period out of respiration through the "tracheate gills.
The tracheate gills themselves, however, have in some cases disappeared, and in others become transformed into the wings of the Flies.
According to Gegenbaur, of all living Tracheate Insects, the Primaeval Flies, or Archiptera, are most closely allied to the common primary form of the Tracheata.
It offers a field for further inquiry, whether the Asaphidae may not have had internal gills, and whether some primitive member of the family may not have given rise to tracheate arthropods.
In discussing the relationship of the trilobites to the various tracheate animals, I have pointed out such palaeontologic evidence as I have been able to gather.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "tracheate" in a variety of sentences. We hope that you will now be able to make sentences using this word.
