Elementary Text-book of Zoology, Volume 1

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Macmillan, 1884 - Zoology - 352 pages
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Page 447 - This remarkable form (Nebalia) was for a long time regarded aa a Phyllopod, and in many of its characters it represents a connectinglink between the PHYLLOPODA and the MALACOSTRACA. The structure and segmentation of the head and thorax resembles that of the Malacostraca, but the terminal region of the abdomen does not present the special form of a caudal plate or telson. In Nebalia we probably have to do with an offshoot of the Phyllopod-like ancestors of the MALACOSTBACA, which has persisted to...
Page 461 - Glaus in his text-book says (I quote from the English edition) : — " The facetted eyes are borne on two movably separated stalks. These were for a long time considered as the anterior pair of appendages, while in fact they are merely lateral portions of the head which have become jointed " ; and elsewhere : " The last abdominal seg nent, which is transformed into a telson.
Page 433 - ISO diani. rudiments of the third and fourth pairs of natatory feet have made their appearance in the form of cushions fringed with setae, and the body consists of the oval cephalothorax, the second, third, and fourth thoracic segments, and an elongated terminal joint. In the Cyclopidae the posterior antennae have lost their secondary branch, and the mandibles have completely thrown off the previously existing natatory feet, whilst in the other families these appendages persist, more or less altered....
Page 333 - ... contained in a secondary cyst. Finally, a tertiary cyst, containing tertiary or granddaughter scolices, arises. In such cases the number of tapeworms which arise from one embryo is naturally enormous, and the parent vesicle may reach a very considerable size, being sometimes as large as a man's head. In consequence of this enormous growth the vesicles frequently obtain an irregular shape; while on the other hand the tapeworms which develop from them remain very small, and carry, as a rule, only...
Page 152 - The Descent of Man, and Selection in Relation to Sex,
Page 333 - Insedivora, and the Omnivora, which receive the bladder-worms in the flesh of the animals on which they feed. The vesicles are digested in the stomach, and the cestode head becomes free as a scolex. The latter is, perhaps, protected from the too intense action of the gastric juice by its calcareous concretions, and at once enters the small intestine, fastens itself to the intestinal wall, and grows by gradual segmentation into a tape -worm.
Page 339 - There is an outer layer of circular muscles and an inner layer of longitudinal muscles.
Page 514 - On the Organs of Reproduction and the Development of the Myriapoda.
Page 447 - The head is not wellmarked off from the thorax ; it bears two pairs of antennae, one pair of mandibles, and two pairs of maxillae. The thorax has usually six pairs of biramous feathery limbs. The abdomen is rudimentary.
Page 317 - The two large trunks open into a common contractile vesicle, which opens to the exterior at the posterior end of the body (fig.

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