. The biology of the amphibia. Amphibians. 24 THE BIOLOGY OF THE AMPHIBIA frog and salamander larvae. The external branchiae early begin to sprout on these arches as a number of small buds. With development a fold appears anterior to the first of these gills. In the frog tadpole this is destined to grow back over the external gills and form an opercular sac which remains in communication with the exterior by one or two small openings, the spiracles. An opercular fold is represented in salamander larvae but it Fig. 11.—The head structures of the early larva of a toad, Gastrophryne carolinensis.
. The biology of the amphibia. Amphibians. 24 THE BIOLOGY OF THE AMPHIBIA frog and salamander larvae. The external branchiae early begin to sprout on these arches as a number of small buds. With development a fold appears anterior to the first of these gills. In the frog tadpole this is destined to grow back over the external gills and form an opercular sac which remains in communication with the exterior by one or two small openings, the spiracles. An opercular fold is represented in salamander larvae but it Fig. 11.—The head structures of the early larva of a toad, Gastrophryne carolinensis. The adhesive organs function at the time of hatching to hold the tadpole to objects in the water. The oro-nasal groove forms the beginning of the nasal chamber. , adhesive organ; , nasal pit; , oro-nasal groove; St., stomodaeum. never completely covers the branchial arches until the time of metamorphosis. The chief difference between the larvae of frogs and sala- manders lies in the mouth region. In most frog tadpoles, lips are formed and these acquire a series of horny teeth arranged in rows above and below a pair of strong mandibles. These nippers are supported internally by a pair of cartilages, called "superior" and "inferior labial ; The former, which articulate with cartilaginous processes of the brain case, are destined to form the premaxillaries of the adult; the latter, the mento-Meckelian bones. The inferior labial cartilages are supported by a pair of short cartilages, the very rudimentary Meckelian, or lower jaw cartilages. Most remarkable is the B .Ad Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Noble, Gladwyn Kingsley, 1894-1940. New York : McGraw-Hill
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Keywords: ., bookcentury1900, bookpublishernewyorkmcgr, booksubjectamphibians
