MUSCULAR SYSTEM 137 



Visceral Muscles. 



Fishes. The visceral muscles of Fishes l have been most 

 satisfactorily investigated in Elasmobranchs, and are classified by 

 Fiirbringer as follows : 



A. Cranial or cerebral muscles (consisting originally of trans- 

 verse or circular fibres) supplied by the V th , VII th , IX th , 

 and X th cerebral nerves. 



1 . Constrictor arcuum visceralium, incl. constrictor superficialis 



dorsalis et ventralis. 



Innervation, 

 Levator labii superioris ~\ 



,, maxilke ,, V. 



, , ] >alpebne nictitantis 2 J 

 ,, rostri ^ 

 ,, hyomandibularis VT1 



Depressor rostri j 

 ,, mandibularis et hyomandibularis J 

 Interbranchiales IX, X. 



Trapezius X. 



2. Arcuales dorsales IX, X. 



3. Adductores, iitd. adductor mandibulse ... V. 



and abductores arcuum branchialium . . IX, X. 



It. S/rinal muscles, originally longitiid- ^ c -, 



i j j- -j j 1-1 .a. j.1. f opino-occipital 6 and 

 inal, and divided, like the other > - , 



11 I spinal nerves, 



trunk-muscles, into myomeres. J 



() Epibranchial spinal muscles, dorsal to visceral skeleton. 



4. Subspinalis Spino-occipital nerves. 



T Spino - occipital nerves, 



5. Interbasales as well as the first 



spinal nerve. 

 (b} Hypobranchial spinal muscles, ventral to visceral skeleton. 



r ri , ( Spinal nerves, and partly 



b. Uoraco - arcuales. me/, coraco- \ r , , , J 



i i-i i -j the last one or more 



branchiales, coraco - hyoideusX c ,, ., , 



and coraco-mandibularis . / f the spmo-occipital 



^ nerves. 



In the Ganoiclei, Dipnoi, Teleostei, Amphibia, and Amniota 

 there are no epibranchial spinal muscles, and the hypobranchial 

 muscles have a very different form from those of Elasmobranchs : 

 in Teleosts, for instance, they are much simplified. In Amphibians, 

 as already mentioned, the rectus system of the trunk is only 



In Cyclostomes there is a remarkable transformation of the cranio-visceral 

 musculature in correspondence with their peculiar cranial skeleton (suctorial 

 apparatus) and branchial basket. It is covered over secondarily by the trunk 

 muscles. 



This muscle lias nothing to do with the other eye-muscles. 

 1 These are spinal nerves emerging from the occipital region of the skull (cf, 

 under Nervous Sj'stem). 



