Trachylinae sentence example

trachylinae
  • Further, two distinct types of otocyst can be recognized in the Hydro medusae; that of the Leptolinae, in which the entire organ is ectodermal, concrement-cells and all, and the organ is not a tentaculocyst; and that of the Trachylinae, in which the organ is a tentaculocyst, and the concrement-cells are endodermal, derived from the endoderm of the modified tentacle, while the rest of the organ is ectodermal.

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  • Brooks regards these organs as sensory, serving for the sense of balance, and representing a primitive stage of the tentaculocysts of Trachylinae; Linko, on the other hand, finding no nerve-elements connected with them, regards them as digestive (?) in function.

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  • In Trachylinae the development produces always a medusa, and there is no polyp-stage.

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  • The Trachylinae, on the other hand, are above all oceanic forms, and have no polyp-stage, and hence there is typically no alternation in their life-cycle.

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  • Hence the Trachylinae are termed " hypogenetic " medusae to contrast them with the metagenetic Leptolinae.

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  • In Trachylinae the polyp-stage is passed over, and is represented only by the actinula as a transitory embryonic stage.

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  • In Trachylinae also the beginnings of a similar metagenesis can be found.

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  • Of doubtful position, but commonly referred to the Trachylinae, are the two genera of fresh-water medusae, Limnocodium and Limnocnida.

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  • Both these medusae have sense-organs of a peculiar type, which are said to contain an endodermal axis like the sense-organs of Trachylinae, but the fact has recently been called in question for FIG.

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  • The possession of a polyp-stage by Limnocodium and Microhydra furnishes an argument against placing them in the Trachylinae.

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  • It is commonly assumed that the Trachylinae are forms which have lost the alternation of generations possessed by them ancestrally, through secondary simplification of the life-cycle.

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  • Brooks [4], who adduces strong evidence for a contrary view, that is to say, for regarding the direct type of development seen in Trachylinae as more primitive, and the metagenesis seen in Leptolinae as a secondary complication introduced into the life-cycle by the acquisition of larval budding.

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