72 CLASS XIV. 



MoDESTE KiLTARY Recherches anatom. sur les Poissons du genre Acipen- 

 ser. Bulletin de Moscom, 1850, li. pp. 389 — 445, PI. vi. vil. ; Osteol. du 

 crdne. 



Spatularia Shaw. Body elongate, naked ; caudal fin below the 

 vertebrae, furnished with a lunate lobe. Head produced beyond the 

 jaw into an appendage, depressed, broad, reticulate, osseo-cutaneous. 

 Branchial aperture large ; operculum extended posteriorly by a cuta- 

 neous lobe, elongate, acuminate. Temporal foramina small. (Os- 

 seous operculum adhering to the suspensory bone of lower jaw, 

 digitato-laciniate posteriorly. Osseous lamella conjoined to the 

 hyoid arch on each side, formed of the concrete rays of the bran- 

 chiostegous membrane). 



Sp. Spatidaria folium, Polyodon folium Lacep. Poiss. i. PI, xir. fig. 3, 

 GuBRiN Inconoc/r., Poiss. PI. 67, fig. 2. There is here no half gill on the 

 giU-cover, as in Acipenser ; the dorsal fin is placed more forward than in 

 that genus, somewhat before the anal fin. Mauduit first described a fish 

 of this kind under the name ot Squalus spatula, Jommal de Physique, 1774, 

 pp. 384 — 386, PI. II. fig. I ; this was without teeth. In other individuals 

 there are numerous very small teeth in two rows in the upper jaw, and in 

 one row in the lower jaw. Rapinesque accordingly has distinguished two 

 genera, Planirostra and Polyodon Lac. ; since however the large specimens 

 (of 3 or 4 feet) are edentulous ^, and the small ones (of h foot or less) pos- 

 sess teeth, the opinion of Valenciennes, that the difference depends upon 

 age, seems to me probable, and at least the adoption of two genera is the 

 less advisable as long as the specific difference is not sufficiently demon- 

 strated. These fishes live in the rivers of North America. The cranium 

 is quite osseous at the upper part, and the sutures (at least those between 

 the frontal bones) are as conspicuous as, for instance, in the pike; so that, 

 according to the characteristics which CuviEK gives for the Chondropterygii, 

 Spatularia ought not to be united to them. The bony head, as far as 

 relates to the jaws and the tongue bone, is figured by J. Mueller, Osteo- 

 lofjie der Myxinoiden, Tab. v. fig. vii ; with which figure a specimen in 

 the Rijks-Museum corresponds. 



Order VI. Ganolepidoti {Holostei Muell.). 

 Skeleton osseous. Body covered with scales, mostly rhombic, 

 not imbricate, osseous, with vitreous substance externally. 



Family VIII. Scmroidei Agassiz. Teeth conical, acute, in a 

 single row in each jaw ; small, crowded teeth behind this row, and 

 in the palate. (Body elongate.) 



1 The specimen, however, described by Mauduit was only 5 inches in size, but 

 perhaps the small teeth were overlooked. Since the teeth are attached to the mucous 

 membrane alone, they are always missing in the skeleton. 



