SILURID^. THE LORICARINiE. 335 



same peculiarity is apparent in the most aberrant of all 

 the apodal fishes^ where the eyes, as in Myocine, are 

 totally wanting. All these facts are in full accordance 

 with our theory (or, rather, we should say they have 

 been the foundations of the theory), that the most 

 aberrant group of a circle is always that which is least 

 organised : the class Acrita in the animal kingdom, the 

 Amphibia among the Vertebrata, the Vermes among the 

 Anmilosa, and innumerable other instances, are too 

 well known to require enumeration ; and we now have 

 a further instance in the circle of the SiluridcB. Fi- 

 nally, we come to the relations of the SorubincB with 

 the cartilaginous order of fishes, and the fissirostral 

 type of birds : the discovery of this group in the rivers 

 of Tropical America, by the lamented Spix, and the 

 masterly description of its peculiar structure by Agassiz, 

 has thrown a light upon this family, we have been 

 waiting for several years ; while the no less important 

 discovery of Sturisoma, by the same traveller, estabhshes 

 two of the most important facts in the natural arrange- 

 ment of the family ; — one showing us a group with 

 the flat prottuded muzzle of the sharks ; the other, 

 the manner in which the whole of the groups we have 

 now review^ed, close into a circle. Did our space permit 

 us to extend these analogies to the Triglidcs, the order 

 Plectognathes, and some other groups, many new and 

 interesting illustrations would result ; but there is so 

 much to be said on the internal relations of the Siluridce 

 among themselves, that we must proceed at once to a 

 more detailed account of the variations of structure ob- 

 servable in each of the sub-families we have now de- 

 signated. 



(27P.) At the head of the LoricariiKE, or mailed cat- 

 fish, stands the genus Loricaria, distinguished by having 

 the whole of the body (excepting the belly), together 

 with the head, covered by large osseous plates, re- 

 sembling rude scales ; the back being furnished with a 

 single dorsal fin. There are not many species, and there- 

 fore it might seem premature to divide the contents of 



