. The Bashford Dean memorial volume :. Fishes; Sharks; Fishes, Fossil. 484 Bashford Dean Memorial Volume The number of occipitospinal roots in Chlamydoselachus, Heptanchus and Spinax is unusually large. In Squalus (Text'figure 120) there are only two or three ventral and two dorsal occipitospinal roots. These nerves united with the first and second spinals are marked hh. in the figure. In Torpedo, a single (ventral) occipitospinal root is present (Daniel, 1934). According to Daniel (1934), the occipitospinal nerves of Heptanchus innervate the subspinaHs and dorsal interarcuales muscles; also,
. The Bashford Dean memorial volume :. Fishes; Sharks; Fishes, Fossil. 484 Bashford Dean Memorial Volume The number of occipitospinal roots in Chlamydoselachus, Heptanchus and Spinax is unusually large. In Squalus (Text'figure 120) there are only two or three ventral and two dorsal occipitospinal roots. These nerves united with the first and second spinals are marked hh. in the figure. In Torpedo, a single (ventral) occipitospinal root is present (Daniel, 1934). According to Daniel (1934), the occipitospinal nerves of Heptanchus innervate the subspinaHs and dorsal interarcuales muscles; also, in elasmobranchs generally, the more posterior of these nerves unite with the first group of spinal nerves to form the cervical. Text-figure 120. A projection, upon a sagittal plane, of the cranial, occipital and anterior spinal nerves of Squalus acanthias. , brachial plexus; , buccalis of seventh nerve; , ramus dorsalis of tenth; gn., first spinal gangUon; hh., hypobranchial bundle; hmd., hyomandibularis; !!.X, lateral line nerve; , mandibularis externus of seventh; , mandibularis internus of seventh; , mandibularis of fifth; , maxillaris of fifth; , ophthalmicus profundus; , and , ophthalmicus superficiaUs of fifth and seventh; , pharyngeal branch of ninth; pi. VII, palatinus of seventh; , post-trematicus of ninth; , pretrematicus of ninth; sp., spiracle; , supratemporalis of ninth; , supratemporalis of tenth; , visceral nerve; y and z, occipitospinal nerves; II, optic; III, oculomotor; IV, trochlearis; VI, abducens; VIII, auditory nerve. From Daniel, 1934, Fig. 220; after Norris and Hughes, 1920, fig. 51 (in colors). plexus which in turn joins the pectoral plexus. The nerves of the cervical plexus separate from the pectoral plexus and pass in front of the girdle to supply the hypobranchial muscles, as in Scyllium and in Squatina (Fiirbringer, 1897). In her summary for the cranial nerves, Hawkes (
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