. The Cambridge natural history. Zoology. ELASMOBRANCHII SELACHII 451 without spines. Tail with a prominent lateral keel on each side. ^ Nictitating membranes absent. Spiracles minute or wanting. Branchial clefts very wide. ISTo oro-nasal grooves. Vertebrae asterospondylic. When fully developed the teeth are solid. In the genus Lamna, which includes the Porbeagle Sharks, the teeth are large, each consisting of a long narrow central cusp, usually with smaller cusps at the base. The common Porbeagle (Z. cornvMca), a fierce pelagic Shark, which may reach a length of 10 feet, frequents the North A
. The Cambridge natural history. Zoology. ELASMOBRANCHII SELACHII 451 without spines. Tail with a prominent lateral keel on each side. ^ Nictitating membranes absent. Spiracles minute or wanting. Branchial clefts very wide. ISTo oro-nasal grooves. Vertebrae asterospondylic. When fully developed the teeth are solid. In the genus Lamna, which includes the Porbeagle Sharks, the teeth are large, each consisting of a long narrow central cusp, usually with smaller cusps at the base. The common Porbeagle (Z. cornvMca), a fierce pelagic Shark, which may reach a length of 10 feet, frequents the North Atlantic and the North Pacific (Fig. 257). It has often been captured off the coasts of Great Britain and Ireland in Mackerel or Salmon nets, or by lines laid for food Fishes. An allied genus, Isurus, is. Fig. 257.—The Common Porbeagle [Lamna cm-nuhica). (From Parker and Haswell, after Bashford Dean.) represented by species on the Atlantic coast of North America, in the Mediterranean and the neighbouring parts of the Atlantic, and also in Asiatic seas. Carcliarodon rondeletii ^ is a pelagic Shark with large, triangular, finely-serrated teeth, without basal cusps, and is found in all tropical and subtropical seas from the Mediterranean to Austraha and New Zealand. It is one of the largest and most formidable of Sharks, and it is said to grow to a length of 40 feet. Nothing is known of its breeding habits. Odontaspis, which has minute pore-like spiracles, but no lateral caudal keels, is a Shark of moderate size, chiefly inhabiting the Atlantic, but found also in the Mediterranean and the Southern Pacific. Its teeth are long and awl-like, with small basal cusps. The Thresher or Fox Shark {Alopecias vulpes) is remarkable for the extraordinary length of the upper lobe of the caudal fin, ' T. J. Parker, 1887, p. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these i
Size: 2651px × 942px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
