184 MB. R- H. BimNE ON THE [Mar, 5, 



Plate XX. 



Fio-. 1, Dinih/sia patagonica (pp. 176-179) ; imperfect skull and mandible, upper 

 iind left lateral (la) aspects, with oral aspect of right maxilla (1?;) 

 and fractured quadrate bone (Ic), nat. size. — From Eed Sandstone, 

 Neuqueu. ag., angular ; d., dentary ; ec, ectopter_ygoid ; ex.occ, 

 exoccipital ; jr., fi-ontal ; inx., maxilla; wa., nasal ; war., external 

 narial opening ; o., projecting otic bone ; oj)., opisthotic; orh., orbit ; 

 pa., parietal ; pr.f., prefrontal ; pr.o., pro-otic ; ^Jif., pterygoid ; 

 ft.f., postfrontal ; qu., quadi-ate ; r., lateral ridge on parietal; s.occ, 

 snpraoccipital ; s.t., supratemporal ; x, fracture. 

 2. Ditto; portion of vertebral column of same specimen, nat. size. 

 11., neural spine ; r., rib. 



All the original specimens are preserved in the La Plata Museum. 



2. Note on the Innervation of the Supraorbital Canal in 

 the Cat-fish {Chim<sra monstrosa). By R. H. Burne, 

 B.A., F.Z.S., Anatomical Assistant in the Museum of 

 the Royal College of Surgeons. 



[Eeceived February 1, 1901.] 



(Text-figare 49.) 



.An excellent historical resxime of the work that has hitherto 

 been done upon the comparative anatomy and more particularly 

 the innervation of the organs of the lateral line, with a discussion 

 of the morphological conclusions that may be drawn from them, is 

 to be found in two recent papers by Cole \ so that for the purposes 

 of this note it will be amply sufficient to briefly sketch certain 

 ascertained facts with regard to the innervation of this sensory 

 system. It has now been shown in several instances that the 

 nerves that supply the lateral-line organs have no real relation to 

 the cranial nerves in whose company they leave the brain, but arise 

 within the brain in common with the auditory nerve from a 

 particular centre — the tuberculum acusticum. Furthermore in 

 almost all cases, when sufficient care is used in the exauiination, the 

 lateral-line nerves are found to enter into a defiuite and constant 

 relationship with certain of the cranial nerves. Thus the lateral- 

 line nerve that supplies the supraorbital canal forms the Ramus 

 ophthalmicus superficialis of the Yllth cranial nerve, that for the 

 suborbital canal constitutes the R. buccalis VII, and that for the 

 hyomandibular canal the Ramus hyomandibularis VII ; while the 

 main lateral canal of the trunk is innervated by the lateralis 

 branch of the vagus. Although this connection of the lateral- 

 line nerves with the Vllth and Xth cranial nerves only is almost 

 universal, it is not so in every case. For instance, in many 



^ Cole: "Observations on the Structure and Morphology of the Cranial 

 Nerves and Lateral Sense-organs of Fishes," Trans. Linn. Soc. vii. 1898, p. 187; 

 and " On the Cranial Nerves of Chimcera monstrosa'' Trans. R. Soc. Edinb. 

 ssxviii. 1897, p. 635, 



