is clearly no other than the mailed or cheloniform type 

 of Elacate, and is consequently the most aberrant of the 

 genus. 



(40.) Having now treated;, in as much detail as our 

 space will admit, on the two typical families of Micbo- 

 LEPTES, we must be even more brief with the three that 

 are aberrant; namely, the Coryphcenidce, the Centris- 

 cid^, and the Echeneidae. The first, indeed, is rich in 

 the number and variety of its forms ; but the two last 

 are represented only by single genera. Having worked 

 out all the divisions of the CoryphcBnidce, and detailed 

 them very fully in our systematic arrangement, the im- 

 possibility of giving further details, in this place, is the 

 less to be regretted. The truth is, that it is utterly im- 

 possible, in two small volumes, to do the least justice to 

 all the groups of ichthyology, since this would absolutely 

 require ^ double extension of the work. Thus strait- 

 ened, we have preferred enlarging upon a few groups ; 

 and leaving the others to be worked out, from the indi- 

 cations here given, by the reader ,• being quite assured of 

 this — that he can come to no other conclusion, in the 

 main, than we have arrived at. 



(41.) The last sub-family of the Zeidce is that of the 

 SphyrcBniTKE, of which the well known Esooc Sphyrcena 

 of Linnaeus is the type. Its close affinity to Elacate 

 has already been mentioned ; and its resemblance to a 

 pike is so strong, that Linnaean writers actually placed 

 it in the same genus. Both affinity and analogy thus 

 conspire to sanction us in the situation we have here 

 assigned to the genus Sphyrcena; it is also obviously 

 connected to Atherina by a new genus, hereafter defined, 

 where we have a fish actually uniting in itself the cha- 

 racters of both these genera. If any further evidence was 

 necessary on this point, we shall find it in the remark- 

 able uniformity with which the great circles of the 

 ScomheridxB and the Zeidte represent each other, thus : — 



