78 



CLASS PISCES. 



-ha, 



B 



the air bladder in some Teleostei, which are fully described in 



the account of that sub-class. 



The Olfactory Organs are a pair of simple pits or sacs, in the 



lining of which the 

 fibres of the olfactory 

 nerve terminate. In 

 the Marsipobranchii 

 the olfactory organ 

 is partly single and 

 presents peculiar re- 

 lations (see account 

 of Marsipobranchii ) . 

 In other fishes each 

 sac usually has two 

 openings, both of 

 which are external 

 except in Dipnoi. 

 In Elasmobra n c h s 

 there is usually only 

 one opening. The 

 internal surface of 

 the sacs is generally 

 increased by folds of 

 the mucous mem 

 brane. 



We know practi- 

 cally nothing about 



FIG. 40. Right membranous labyrinth of Chimaera, seen f,hp <;fnsf of taste 

 from the median side (from Wiedersheim, after Retzius). 



aa ampulla of anterior vertical canal ; etc auditory nerve ; The tactile Sense is 

 ade opening of ductus endolymphaticus ; ae ampulla of " 



horizontal canal ; ap ampulla of posterior vertical canal ; J^Q doubt Specially 

 ass process of the sinus utriculi ; ca, anterior, c-p posterior 



vertical canal ; ce horizontal canal ; cr crista acustica served bv the lips 

 ampullae ; de ductus endolymphaticus, which opens at ade * 



through the skin ha ; mn macula acustica neglecta ; ms and their appendages, 

 macula acustica sacculi (the macula ac. utr. rec is on the 



other side and not properly visible) ; pi papilla acustica and bv special parts 

 lagenae (the lagena, however, can hardly be said to be J 



present in this form) ; branches of auditory nerve rota to of the appendages 

 anterior ampulla, rae to horizontal ampulla, rap to pos- 

 terior ampulla, rec to macula acustici utriculi, rs to which are riclllv 

 macula sacculi and lagenae, ru to macula recessus utriculi ; 



s saccule ; sp sinus utriculi posterior, ss sinus utriculi innervated (e.g. 

 superior ; u utricle. 



Trigla.) 



The system of embedded epidermal* sense organs which are 

 found in all fishes requires a detailed description. 



* Levdig, Lehrbuch d. Histologie des Menschen u. d. Thiere, 1857. Solger, 



rec 



rs 



