411 



head, the shape of the body, and the position of the legs. The 

 ducks have the bill flattened in a horizontal and the head in a ver- 

 tical plane, and the legs placed so far forward that they can move, 

 though awkwardly, on land ; the neck is long and slender, and 

 the body short and chubby. The auks have the head com- 

 pressed in a horizontal and the bill in a vertical plane ; the body 

 is very long and flattened vertically ; the legs are entirely be- 

 hind, and the tibia is so bound down by the integuments, that the 

 animal, on land, often tumbles forward, and assumes when stand- 

 ing an upright position. 



The paper was accompanied by drawings, and by 

 tables giving the proportions of the skulls and skeletons, 

 and showing the characters of the families. 



Prof. Agassiz made some remarks on two Pomocentri- 

 dcB from the Florida reefs, of the genera Glyphisodon and 

 Pomacentrus, the latter being a new species called by 

 him P. meleagris. 



The family of Discoboli, of which the Lump-fish is the chief 

 representative, is very interesting both anatomically and zoologi- 

 cally. Swainson arranged the lump-fish with the lamprey-eel, 

 which is as bad as placing the bat among the bii'ds. Cuvier 

 placed it with the malacopterygians, with the Gadidce and Pleura- 

 nectidce. J. Miiller separated the Discoboli from malacoptery- 

 gians, and placed them with the acanthopterygians, where they 

 belong ; but from the fact that the ventrals are united into a 

 disk, he erroneously placed them in a family Cyclopodi, with Go- 

 bius, separating Eleotris from the family. The genus Echeneis, 

 according to Prof. Agassiz, belongs among the scomberoids. He 

 gave some of the characters of the genera Cyclopterus, Liparis, 

 Gobiesox, and Lepadogaster, of the family Discoboli ; — in Lepado- 

 gaster there are two pairs of pectorals and two pairs of ventrals, 

 one pair of which consist each of folds of skin only, and are not true 

 fins ; the membranous fold of the second pectorals contains fibrous 

 rays, and is attached to the shoulder bone, the membranous ven- 

 tral fold is attached to the styloid bone. These structural fea- 

 tures render a separation of Lepadogaster and Cyclopterus as 



