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Bashford Dean Memorial Volume 



being wholly independent, as Merritt Hawkes describes and shows them. Further- 

 more, it is to be noted that the origin of her ophthalmicus superficiaHs trigemini from that 

 small s\^eUing on the inner side of the Gasserian gangHon from which the ophthalmicus 

 profundus has its origin, would seem to indicate that it is a portio ophthakaici profundi 

 and not a trigeminus ner\'e, and its origin in Squalus, as given by Landacre (1916), and its 

 distribution in the same fish, as given by Norris and Hughes (1920), are not unfavourable 

 to this interpretation of it. The nerve is, however, said by Norris and Hughes to arise 

 from ganglionic cells in the Gasserian ganglion, while the fibers of the ophthalmicus profundus 

 simply traverse that gangHon. The ner\-e, as I find and define it in Chlamydoselachus, is 

 large, and running forward dorsal to all the ner\'es and muscles of the orbit, traverses the 



.ootA. 

 •RootB. 



S.Op.VII-: 



s.op.v- 



Fro'. 





A- 



-S.Op.V 

 {t-Fto. 



,vm jj \^\yys.op.vR 



B- Manyy ; ^^ucc 

 JVfax.K 



Text-figure 119. 

 Gangliated roots of fifth, seventh and eighth cranial ner\'es of Chlamy- 

 doselachus: A, lateral view; B, medial (inner) view. 



Bucc., ramus buccalis VU; H., gangUon of the trvmcus hyomandibularis (i.e., the true 

 ganglion of the facialis, combined with the acustico-hteraHs ganglion); Man. V and Max. V, 

 mandibular and maxillary divisions of the facial ner%'e; P.I., pars intermedia; Fro., profundus 

 branch of the facial; R-C, ramus communicans; R_ V., root of trigeminal nerve; S.Op.V 

 and S.Op.VII, superficial ophthalmic divisions of the fifth and seventh cranial nerves. 

 After Hawkes, 1906, Figs. 2 and 3, pL LXVm. 



preorbital foramen and reaches the dor^ surface of the nasal capsule, where it immediately 

 breaks up into numerous branches which spread out, fan-shaped, and innen.'ate the sensory 

 organs of the supraorbital laterosensory canal and the supraorbital ampullae, as shown in the 



figures. As the ner\'e traverses the orbit a number of branches are sent upward through the 

 foramina supraorbitaHa to the related portion of the supraorbital canal. 



The maxiUar}' and the mandibular rami of the trigeminal nen.'e (Max. V. and 

 Man. V. in Text-figure 119) come off separately from the Gasserian gangHon; there is 

 no common maxillo-mandibular trunk. This condition is somewhat exceptional ainong 

 elasmobranchs. Since, in Chlamydoselachus, the angle of the jaw is situated far posteriorly, 

 the mandibular nerve leaves the maxillary early in its course and passes over the posterior 

 wall of the orbit to reach the angle oi the mouth, as m Acanthias. The mandibular 

 nerve does not supply the large median transverse muscle bridging the halves of the lower 

 jaw in the gular region (Fiirbringer, 1903; Hawkes, 1906; Luther, 1909; AlHs, 1917 and 

 1923). This unique feature has been fully discussed (p. 399) in the section on the 

 muscular system. 



