. Biology of the vertebrates : a comparative study of man and his animal allies. Vertebrates; Vertebrates -- Anatomy; Anatomy, Comparative. //' Biology of the Vertebrates a small pair of mandibular canals on the lower jaw and a supratemporal over the top of the head connecting the two sides just posterior to the spira- cle. The lateral line canals and the supratemporal are innervated by the vagus (Xth) nerve, except for a small part near their junction to which the glossopharyngeal (IXth) nerve goes. All the other canals are supplied by the facial (Vllth) nerve. Scattered pit organs are isolat
. Biology of the vertebrates : a comparative study of man and his animal allies. Vertebrates; Vertebrates -- Anatomy; Anatomy, Comparative. //' Biology of the Vertebrates a small pair of mandibular canals on the lower jaw and a supratemporal over the top of the head connecting the two sides just posterior to the spira- cle. The lateral line canals and the supratemporal are innervated by the vagus (Xth) nerve, except for a small part near their junction to which the glossopharyngeal (IXth) nerve goes. All the other canals are supplied by the facial (Vllth) nerve. Scattered pit organs are isolated neuromasts, each sunk into a separate pit. In some fishes certain of these pits may be arranged in rows which occupy the same position as a groove or canal in another species. Supratemporal Canal Supraorbital Canal. Lateral-Line Canal Hyomandibular Cana Mandibular Canal- Infraorbital Canal Fig. 672. Right-lateral view of the lateral-line system of the head of Squalus. (From Sayles, Manual for Comparative Anatomy, copyright 1938, by permission of The Macmillan Company, publishers.) Whenever lateral fins are so placed that they would naturally extend over a portion of the lateral line, or by their movement cause an agitation in the water which would interfere with the reception of the stimulus produced by external currents of water, the part of the lateral-line canal interfered with may curve out of the way in a detour, thus avoiding interference (Fig. 673). Various stages of elaboration of the lateral line may occur at the same time in different regions of the same fish, or at different times in the course of development. The eel, Anguilla, for example, during the early "lepto- cephalus stage," has only isolated pit organs present on the head region. Young fingerlings develop a lateral line closed anteriorly but open pos- teriorly, while the adult has the entire system insunken and closed except for craterlike pores along the line. Among amphibians rheoreceptors are
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