110 CLASS XIV. 



membrane with 10 — 11 rays. Scales large. Pectoral fins elongate. 

 Caudal fin forked, with inferior lobe larger. 



Flying fishes. In some species the pectoral fins are as long as the body ; 

 by means of these long fins these fish can keep themselves for a time above 

 the water. (See above, p. 5 1). They are all marine fishes, of which more 

 than thirty species are now known, though LiNNiEUS recorded two of them 

 onlj^, namely Exocoetus volitans L., (Cuv. et Valenc. Poiss. xix. PI. 559), 

 principally in the Mediterranean Sea, and Exoc. evolans L., Bloch Ichth. 

 Tab. 398, occurring in the North Sea, the Atlantic, and also in the 

 Southern Pacific, 



Family XIX. Mormyrini. Upper margin of mouth formed 

 by the intermaxillary and supramaxillary bones ; mouth small ; 

 teeth in intermaxillary bone and lower jaw compressed, small, 

 emarginate or tricuspid; teeth in vomer and tongue subulate, 

 crowded. Branchial aperture small, linear ; branchiostegous mem- 

 brane with few (5 — 6) rays. Body compressed, covered with small 

 scales ; head with naked thick skin. Dorsal fin single, often long. 

 Swimming-bladder simple, furnished with a duct. 



Mormyrus L. 



Fresli-watev fishes fx'om Africa, of which several species are now 

 known. They differ from the fishes of the precetling family by a 

 longer intestinal canal, and two blind tubes {apj^endices pyloricw). 

 At the posterior margin of the mastoid bone (see above, p. 20,) 

 there is a large oval apei-ture, which was discovered by Heusinger 

 in Mormyrus cyprinoides, and which is covered by a scale-like os 

 sujiratemporale (see above, p. 22 note) ; nnder the opening lies the 

 sac of the vestibule. 



See Meckel's Archiv fur Anat. w. Physiol. 1826, s. 324 — 327, Tab. iv. 

 figs. 8—10. 



At the tail, which is thickened, are situated on each side under the 

 lateral muscle two elongate organs, which cause the thickening, divided 

 into a number of spaces, and probably to be regarded as electric organs, 

 although, as far as I know, nothing has yet been ascertained respecting the 

 electric power of these fishes. 



Erdl and Gemminger observed this arrangement in Mormyriis oxy- 

 7'hynch us and M. dorsalls, Koelliker in Mo7'my7'us lonffi2nnnis Hvevpell ; 

 see Koelliker's description with figures, Berichte von der honigl. Zooto- 

 mischen Anstalt zu Wiirzhurg, 11. 1849, s. 9—13. See also J. Hyrtl, 

 Anatomische M ittheilungen iiber Mormyrus und Gymnarchus, Wien, 1856, 

 4to. Mit 6 Tafeln. (xii. Bd. der Denkschr. der math, nattir, Classe der 

 Kaiserl. Akad. der Wissensch.) 



Hyrtl has figured remarkable diverticula at the bulb of the arterial stem 

 of the gills. 



