PISCES. 75 



BONATERRE Enc. Meth., Poiss. PL 99, fig. 408, BLOCH, SCHNEIDER Syst. 

 Ichth. Tab. 80 is Amia, lentiginosa YAL. 



The swimming-bladder is cellular and double. There is no gill on the 

 gill-cover. Compare H. FRANQUE Diss. inaug. nonnutta ad Amiam calvam 

 L. accuratius cognoscendam, Berolini, 1847, under the direction of J. 

 MUELLER, with figure of the skeleton, the brain, the heart, and the viscera. 



B. Arterial bulb elastic, with two valves at the base. (Comp. 

 above, p. 60.) 



SECTION IV. Osteopterygii. 



Fins supported by osseous rays. Skeleton osseous. Dorsal 

 column composed of distinct vertebrae. Branchiae free. (Optic 

 nerves decussating or placed cross- wise with respect to each other.) 



ORDER VII. Lophobranchii Cuv. 



Branchial laminae broad, clavate, not numerous, arranged in a 

 double row along the branchial arches, folded transversely. Bran- 

 chial aperture small, superior, with a large operculum fixed to the 

 skin throughout nearly its entire circumference. Rays of branchio- 

 stegous membrane small, very thin. Body loricate, angular. 



Gluster-gilled. The singular structure of the gills was first, as it 

 seems, remarked by TIEDEMANN (MECKEL'S Archivfur die Physiol. 

 n. 1816, s. 110112, Tab. n. fig. 7, 8), but more accurately inves- 

 tigated by RATHKE (Ueber den Kiemenapparat, s. 50, 51, Tab. iv. 

 fig. 2) and by E.ETZIUS. The deviation from the usual structure of 

 gills is, according to these researches, rather apparent than essential. 

 RATHKE denies gill-rays to these fishes, which however, according to 

 my observations, is incorrect. 



All the species belonging to this order are of small size; only 

 a few grow to the length of 1'. In the sea-horse (Syngnathus 

 hippocampus L.), a species of this order, a hybernation has been 

 observed, during which the respiration is diminished; see RUSCONI 

 in MECKEL'S Archivf. d. Physiol. v. s. 268 270. 



The eggs are carried under the abdomen or at the base of the 

 tail, mostly under two longitudinal folds of skin which close like 

 folding doors, and in fact, as ECKSTROEM and other Northern writers 

 have observed, by the r niale, to whose protection the female consigns 

 them, and with whom the young ones, when born, continue to live 

 for a time. Die Fische in den Scheeren von Morko, beschrieben von 



