The origin of vertebrates / by Walter Holbrook Gaskell.

  • Gaskell, Walter Holbrook, 1847-1914.
Date:
1908
Catalogue details

Licence: In copyright

Credit: The origin of vertebrates / by Walter Holbrook Gaskell. Source: Wellcome Collection.

Provider: This material has been provided by King’s College London. The original may be consulted at King’s College London.

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    CHAPTER IV The Evidence of the Respiuatouy Appakatus I'AGK Branchiee considered as internal brancliial appendages—Innervation of branchial segments—Cranial region older than spinal—Three-root system of cranial nerves: dorsal, lateral, ventral—Explanation of van Wijhe's segments— Lateral mixed root is appendage-nerve of invertebrate—The branchial chamber of Ammocostes—The branchial unit, not a pouch but an appendage —The origin of the branchial musculature—-The branchial circulation—The branchial heart of the vertebrate—Not homologous with the systemic heart of the arthropod—Its formation from two longitudinal venous sinuses— Summary 148 CHAPTER V The Evidence op the Thyroid Gland The value of the appendage-unit in non-branchial segments—The double nature of the hyoid segment—Its branchial part—Its thyi-oid part—The double nature of the opercular appendage—Its branchial part—Its genital part— Unique character of the thyroid gland of Ammoccetes—Its structure-^ Its openings—The nature of the thyroid segment—The uterus of the scorpion—Its glands—Comparison with the thyroid gland of Ammoccetes— Cephalic generative glands of Limulus—Interpretation of glandular tissue filling up the brain-case of Ammoccetes—Function of thjToid gland— Relation of thyroid gland to sexual functions—Summary .... 185 CHAPTER VI The Evidence of the Olfactory Apparatus Fishes divided into Amphirhinse and Monorhinse—Nasal tube of the lamprey —Its termination at the infundibulum—The olfactory organs of the scorpion group—The camerostome—Its formation as a tube—Its derivation from a pair of antennse-Its termination at the true mouth—Comparison with the olfactory tube of Ammoccetes—Origin of the nasal tube of Amraocoetes from the tube of the hypophysis—Direct comparison of the hjTpophysial tube with the olfactory tube of the scorpion group—Summary CHAPTER VII The Prosomatic Segments of Limulus and its Allies Comparison of the trigeminal with the prosomatic region—The prosomatic appendages of tlie Gigautostraca—Tlicir number and nature—Endognaths and ectognath—The motastoma—The coxal glands—Prosomatic region of Eurypterus compared with that of Ammoccetes—Prosomatic segmentation shown by marks on carapace—Evidence of ca3lomic cavities in Limulus— Summary