Turbellarium in a sentence

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How to use turbellarium in a sentence. Turbellarium pronunciation.

In order to understand the further development of the gastraea, we must pay particular attention to: (1) the careful study of the embryonic stages of the amphioxus that lie between the gastrula and the chordula; (2) the morphological study of the simplest Platodes (Platodaria and Turbellaria) and several groups of unarticulated Vermalia (Gastrotricha, Nemertina, Enteropneusta).
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It is now usual to distinguish four classes of Platodes: the two free-living classes of the primitive worms (Platodaria) and the coiled-worms (Turbellaria), and the two parasitic classes of the suctorial worms (Trematoda) and the tape-worms (Cestoda).
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They have been hitherto, as a rule, regarded as a special order of the Turbellaria, and associated with the Rhabdocoela; but they differ considerably from these and all the other Platodes (flat worms) in the absence of renal canals and a special central nervous system; the structure of their tissue is also simpler than in the other Platodes.
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Most of the Platodaria have not the muscular pharynx, which is very advanced in the Turbellaria and Trematoda.
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The Turbellaria, with which the similar Platodaria were formerly classed, differ materially from them in the more advanced structure of their organs, and especially in having a central nervous system (vertical brain) and excretory renal canals (nephridia); both originate from the ectoderm.
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The Turbellaria are still represented by a number of different forms, in both fresh and sea-water.
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It is noteworthy that the mouth of the Turbellaria (like the primitive mouth of the Gastraea) may, in this class, change its position considerably in the middle line of the ventral surface; sometimes it lies behind (Opisthostomum), sometimes in the middle (Mesostomum), sometimes in front (Prosostomum).
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In most of the Turbellaria there is a narrow cavity, containing a number of secondary organs, between the two primary germinal layers, the outer or animal layer of which forms the epidermis and the inner vegetal layer the visceral epithelium.
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They are first met in the Turbellaria, and have been transmitted direct from these to the Vermalia, and from these to the higher stems.
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Finally, there is a very important new organ in the Turbellaria, which we do not find in the Cryptocoela (Figure 2.239) and their gastraead ancestors-the rudimentary nervous system.
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Many of the Turbellaria have also special sense-organs; a couple of ciliated smell pits (na), rudimentary eyes (au), and, less frequently, auditory vesicles.
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On these principles I assume that the oldest and simplest Turbellaria arose from Platodaria, and these directly from bilateral Gastraeads.
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Next to the ancient stem-group of the Turbellaria come a number of more recent chordonia ancestors, which we class with the Vermalia or Helminthes, the unarticulated worms.
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Further, the cilia that cover the whole surface of the Turbellaria are confined in the Gastrotricha to two ciliated bands (f) on the ventral surface of the oval body, the dorsal surface having bristles.
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Both classes have a complete ciliary coat on the epidermis, a heritage from the Turbellaria and the Gastraeads; also, both have two openings of the gut, the mouth and anus, like the Gastrotricha.
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The Nemertina were formerly classed with the much less advanced Turbellaria.
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In their internal structure they approach the Turbellaria on the one hand and the higher Vermalia (especially the Enteropneusta) on the other.
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Man's ancestors have substantially the organisation of simple Platodes (at first like the cryptocoelic Platodaria, later like the rhabdocoelic Turbellaria).
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Even in the Platodes, especially the Turbellaria, we find an independent nervous system, which has separated from the outer skin.
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Examples of Turbellarium

Example #1
We have to consider the Platodes first, because they are on the border between the two principal groups of the Metazoa, the Coelenteria and the Coelomaria.
Example #2
The vegetal entoderm that lined their simple gut-cavity served for nutrition; the ciliated ectoderm that formed the external skin attended to locomotion and sensation; finally, the two primitive mesodermic cells, that lay to the right and left at the ventral border of the primitive mouth, were sexual cells, and effected reproduction.
Example #3
We have only to consider the first two of these classes; the other two are parasites, and have descended from the former by adaptation to parasitic habits and consequent degeneration.
Example #4
With the former they share the lack of body-cavity, anus, and vascular system; with the latter they have in common the bilateral type, the possession of a pair of nephridia or renal canals, and the formation of a vertical brain or cerebral ganglion.
Example #5
Most of the Platodes of this group (Aphanostomum, Amphichoerus, Convoluta, Schizoprora, etc.) are very soft and delicate animals, swimming about in the sea by means of a ciliary coat, and very small (1/10 to 1/20 inch long).
Example #6
The primitive worms (Platodaria) are very small flat worms of simple construction, but of great morphological and phylogenetic interest.