IIAC-KISIIK.S. 



1201 



ijroptT, but only with tlic iibo\e-iiieiitioiied eai'tilaj^inoiis 

 rods, situated in its t'oreniost part. The six <^ill-sacs 

 (hr) vu each side couimunicate inwards by means oi' a 

 siiort transverse duct with the a'sophagus; outwards 

 eacii of them emits a longer duct {hr'), curving down- 

 wards and outwards. These latter ducts coalesce on 

 each side into a single canal, thus tinding an orifice 

 on the two outer sides of the bodj' at an opening 

 situated far back, the two outer hravchkil apertures 

 (rtg. :i:)H, s; fig. 868, A). 



A^^rroiis fo/sfeni. The brain of 3L/.rine exhibits a 

 rudiuientarx structure with decidedly retrogressive cha- 

 racters (figs. 357 and 359). As mentioned above, the 

 investing cerebral ca])sule consists of cartilage under- 



Fig. 358. Braiiclii:il apparatus, heart, Ijrancliial artery, and (oscipljatciis 



of Mijxiiie gliitiiiosa, after Johannes MCli.er. Nat. size. 

 r. lesophagus; i, inner branchial ducts; ir, gill-sacs; br\ outer hran- 

 ohial ducts, which coalesce and have a common opening at s, the outer 

 branchial aperture; a, atrium of the heart; v, its ventricle; ab, branchial 

 tirtirv, vvliirli sends n division to each sac; d, flaps of skin, folded hacU. 



neatli alone; its sides and roof are of a fibrous texture. 

 The brain is first enveloped in a thin, blood-vascidar, 

 connective tissue, a kind of pia mater, which descends 

 into and fills the cereliral sulci. Seen from above (fig. 

 .l.V.l) the naked brain is triangular, with tiie base of 

 the triangle directed forwards. By a dorsal longitu- 

 dinal sulcus in the median line a bisection into two 

 lateral halves is indicated. In each lateral Iialf five 

 divisions, bounded by transverse sulci, may be traced, 

 namely, beginning from in front, the olfactori/ brain, 

 forehraiu, midhrain, hindhrain, and afterhrain. Of the 



'ttreenhraiii there api)ears dorsnlly, in the angle between 

 tlie f'orebrain and midbiain, a small, rounded or oval 

 protuberance, tlie (/(iiif/lioii liubenuke, usuallj- consisting 

 of a right and a left lobe; but of the epiphysis itself 

 not a trace can else be detected; on the ventral side 

 is a small infundibulum with a lamellar a|)pendage, 

 the liifjwplii/sis. Tlic afterbrain (medulla oblongata) is 

 strongly develo])ed; its anteriorly dilated central canal 

 advances tlirough tiie midbrain to a cu'cal termination, 

 somewhat ix^fore the posterior half thereof. The third 

 ventricle is oblitt'rated, with the exception of two small 

 vestiges. Of lateral ventricles there is no trace. No 

 ej)endj"mal pallium, like tliat of the Teleosts and I'efro- 



Fig. 359. Brain of Mi/xiiie f/lutiiiosa, seen from above. X 7. 



«, olfactory lobe; i, forcbrain ; c, midbrain; d, hindbrain; e, after- 

 brain; /, ganglion lmbenula»; g, spinal cord; li, nasal duct with carti- 

 laginous rings; ?', olfactory organ with cartilaginous basket; k, eye; 

 /, o)itic nerve; m, trigeminus; h, facialis (?); 0, trigeminus (?); p, 

 acoustic nerve; q, vagus; »', sensory roots of spinal nerves. 



mi/zon larvtv, is to be found. It is hence impossible 

 for the present to determine with certainty in the adult 

 state whether the forebrain of ^fi/xine merely corre- 

 sponds to the cor[)ora striata, or whether the cerebral 

 pallium also enters into its structure. 



The nerves issuing from the brain on each side 

 are: olfactorius, opticus, tric/eminus, facialis, acKsficus, 

 and raff us; of the others no trace can be seen. 



