878 MR. AV. WOODLAND ON THE [Nov. 27, 



parallel with the infei'ior rectus muscle in both orbits, and was 

 probably in connection with the lining membrane of the orbit. 



As described below, a distinct supra-neural vein was present 

 in the hind caudal vertebrae. 



The Nervous System. 



The brain of Centrophorus calceus (PL LX. fig. 15) is of the 

 normal selachian type, with however modifications of shape 

 adapted to the elongated snout of the animal. The extreuiely 

 long slender olfactory lobes a^e well-marked oflT from the pros- 

 encephalon, for example, and this latter is also well-defined and 

 distinctly separated into two lobes by a median longitudinal groove. 

 The thalamencephalon is similai-ly elongated in adaptation to the 

 shape of the head. The large cerebellum has both longitudinal 

 and transverse constrictions dorsally, the optic lobes and restiform 

 bodies are large and the medulla oblongata broad. The tracts of 

 nerve-fibres described by Jackson & Clarke as present in the floor 

 of the cavity of the medulla oblongata of EcldnorMnus sjnnosiijS 

 — the anterior pyramids, teretial tracts, ganglionated tracts 

 (especially well-marked), and " external strands of the medulla 

 oblongata" — are all present and well-marked in the case of 

 C. calcevs. On the ventral surface the infundibulum and pituitary 

 stalk and body are well-defined, and the saccus vasculosus extends 

 right round the base of the pituitary. body. 



The cranial nerves of C. calceus are, at least judging irom a 

 comparison of them with those of Scylliwm canictda, Hexanchus ^% 

 Echinorhinus spinosus ^°, Ghimcera '"^^ Spinax acanthias ~°, Lceviar- 

 gus ^', Mustela Icevis -^, Eaja "", and the Torpedo ^^, peculiar, and 

 the interpretations I shall put upon the various branches of the 

 trigeminal and facialis are ofiered as suggestions only. HoAvever, 

 though my interpretations of the facts may turn out to be in- 

 correct, I can absolutely guarantee the correctness of the facts 

 themselA^es, and this being the case, my figures may be of some 

 use to speculatiA^e nerA-e-morphologists. 



There is nothing to remark upon concerning the olfactory, 

 optic, oculo-motor, abducent, auditory, glosso-pharyngeal, and 

 vagus nerA'es : they are all more or less of the ordinarj^ Dog- 

 fish type. With regaixl to the patheticus or trochlear nerve, 

 this in the left orbit apparently sends two branches to the 

 superior oblique muscle but only one in the right, and in both 

 orbits the nerA^e comes into contact for a quarter-of-an-inch or so 

 with the ophthalmicus superficialis of the facial Avhich runs 



-5 " Ueber die Kopfnerven von Hexanchus und ihr Verhaltniss zur " Wirbeltheorie 

 des Sclmdels." C. Gegenbaur. Jena. Zeitschr. vol. vi. 1871. ' '.j 



26 ' Das peripberische Nerveusystem der Fische.' H. Stannius. Rostock, 1849. 



-7 " On tbe Cranial Nerves of Elasmobvancli Fishes. Preliminary Communica- 

 tion." J. C. Ewart. Proc. Roy. Soc. vol. xlv. 1889. ^ 



2S " The Lateral Sensorj- Canals, tbe Eye- Muscles, and the Peripheral Dis- 

 tribution of certain of the Cranial Nerves of Mnstehts la-vis." E. P. Allis. Q. J. M. S. 

 n. s. xlv. (2) 1901. 



29 "The Cranial Nerves of the Torpedo (Preliminary Note)." J. C. Ewart. 

 Proc. Roy. Soc. vol. xlvii. 1890. 



