338 Prof. OwEn’s Description of the Lepidosiren annectens. 
tremities, and are more elongated, forming the first of the caudal series of 
vascular arches already described. 
The pelvic arch is represented by a single piece of cartilage of a crucial form *; 
the transverse pieces curve slightly upwards, and we may suppose them to re- 
present the iliac elements of the os innominatum : the articular surface for the 
basis of the posterior extremity is near the anterior part of the cartil 
support of the rudimental ventral fin consists of a single 
milar to that of the anterior extremity, but thicker ; 
counted in this ray, 
age. This 
-jointed soft ray T, si- 
about forty joints may be 
in many of the larger of which there were ossific deposits. 
In reviewing the principal characters above noticed of the skeleton of the 
Lepidosiren, we obtain good evidence of its ichthyic nature. 
If, indeed, the 
species had been known only 
by its skeleton, no one could have hesitated in 
referring it to the class of Fishes; but in that class it would have offered a 
most singular and interesting combination of the car 
tilaginous and osseous 
types. 
fishes; but the supe- 
ning the cartilaginous 
re characteristic of the 
ents an extremely novel 
th as regards its partial 
It is only in the higher. 
palatine and pterygoid bones are 
the Siren: but no v 
sphenoideum basilare” as ; 
seen in its fully ossified state. As the basis 
t x A 
condition analogous to that which character} presents 
* Tan. XXII. fig. 4, y. 
