330 Prof, Owen'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 embryonic 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 onesf ; 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 the 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 %. 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 

 six soft papillose processes, of a triangular form ; two of these, which are 

 situated in the middle line, consist of a transverse row of papillae ; the poste- 

 rior ones are membranous, and the papillae are confined to their margin and 

 outer surface : they occupy the notches of the broad and strong dental plate. 



* Tab. XXIII. fig. 2, «. f lb. b. 



X In the Siren as well as in the Proteus, Cuvier expressly states, that the nasal cavities communicate 

 ■with the mouth ; and attributes to the ingenious naturalist Oken his attention to this circumstance as 

 a distinguishing character between Fishes and Reptiles. — See Ossemens Fossiles, 8vo., 1837, torn. x. 

 p. 339. § Tab. XXVII. fig. 2. 



