544 MULLER ON THE STRUCTURE OF THE GANOIDS, 
The newly obtained Lepisosteus has still more numerous valves 
in the arterial trunk of the heart than the specimen which I 
examined in Paris; the arrangement of the valves is also differ- 
ent. In the Parisian specimen there were five equally developed 
longitudinal rows of eight valves, thus in all forty valves. In 
those recently examined there are eight longitudinal rows of 
valves ; among these four rows are larger, and between them 
there are four rows of smaller ones. The principal rows con- 
tain nine valves, the smaller ones partly less. If all the valves 
were equally developed there would be seventy-two; however, 
only from about fifty-four to sixty are developed. This distinction 
alone indicates a specific difference. The specimens obtained 
by Dr. Roemer are the ordinary long-snouted species, Lepisos- 
teus bison, De Kay, ‘ Zoology of New York,’ pt. 3. Albany, 
1842, p. 271, tab. 43. fig. 139. (Lepisosteus osseus, Agass. 
Poiss. Foss. i. 2. p. 2, tab. A. fig. inf. and sup.) In the Pa- 
risian specimen the snout was shorter, as in the Caiman, Encycl. 
Meéthod. tab. 71, fig. 292. Lepisosteus platyrhynchus, De Kay, 
p- 273, tab. 43. fig. 137. JL. semiradiatus, Ag., Poiss. Foss. ii. 
tab. A. fig. ined., which appear to be identical. Spatularia has 
four longitudinal rows of valves, with three in each, within the 
muscular arterial trunk. 
An important new fact in the anatomy of the Ganoids relates 
to those which have not the opercular gill, Polypterus and Spa- 
tularia. 
In those Ganoids which are not furnished with the respiratory 
opercular gill, the gill-artery still appears necessarily to give a 
branch to the operculum, so that this artery must be regarded 
as equivalent to the above gill, or as an aortic arch. I observed 
this accidentally in Polypterus bichir, and it was the same in 
several specimens. I then found the same branch of the gill- 
artery going to the operculum in the Spatularia sent me by Dr. 
Roemer*, 
* This specimen is one foot and a half long, and has teeth in the upper jaw, 
palate-bones, lower jaw, and on the anterior part of the two first gill-arches, 
hence Polyodon folium, Lacép., which is however perhaps only Planirostra 
edentula in a young state; for all the specimens hitherto examined which had 
teeth were young, and those without them were larger. See Vergl. Anat. der 
Myzinoid, i. p. 148. On the summit of the tail there are fulera, as in the Stur- 
geons, and the sides of the upper fold of the tail-fin are also furnished with 
longitudinal osseous plates. The orifice of the pharynx and the posterior and 
inferior circumference of the gill-cavity are covered with small three-valved 
cordiform scattered scales. Lacépéde was wrong in ascribing five gill-arches 
