330 Prof. OweEn’s Description of the Lepidosiren annectens. 
reaches the ventral extremities, where it bends down to midway between the 
dorsal and ventral margins, and so continues to the end of the tail. | 
The rudimental filamentary fins, the analogues of the four ordinary extremi- 
ties in the Vertebrata, permanently represent in the present singular animal 
the earliest embryonie condition of the pectoral and pelvic members. They 
are round, filiform, gradually attenuated to an undivided point, resembling 
tentacles or feelers rather than fins or legs, and doubtless restricted to their 
tactile functions. Each filiform member is supported by a single-jointed, soft, 
or cartilaginous ray. The pectoral tentacles* are somewhat shorter and more 
slender than the ventral onest ; the former are two inches, the latter two inches, 
four lines in length. 
The branchial apertures are narrow vertical slits, four lines in extent. 
The eyes appear externally as two small round flat spots, of a lighter colour 
than the surrounding integument ; they are situated seven lines from the end 
of the snout, and nearly the same distance apart from one another. Each of 
these simple visual organs measures one line and a half in diameter; it is 
not defended by any palpebral folds of the skin; the cornea is thin, suffi- 
ciently transparent to allow the lens to be visible even in th 
e specimen pre- 
served in spirits. 
The nostrils are situated at the under part of the upper lip, 
within the opening of the mouth. They appear as two small perforations 
leading to blind sacs afterwards to be described 4. The opening of the mouth $ 
is wide, and defended by well-developed fleshy lips. The skin at the angles 
of the mouth is thinner than at the rest of its circumference, and the upper 
lip folds over the lower one from the angle to near the fore part of the mouth; 
here the lips are thick, smooth and rounded; the lower lip is the thickest. 
About a line behind the lower lip, between it and the teeth, there project 
nix soft papillose processes, of a triangular form; two of these, which are 
situated in the middle line, consist of a transverse row of papillæ; the poste- 
rior ones are membranous, and the papillæ are confined to their margin and 
outer surface: they occupy the notches of the broad and strong dental plate. 
* Tas. XXIII. fig. 2, a. 
T Ib. 5. 
