^04t Mr. BeH on a new Genus of Iguanidee. 



these four, bat, for the most part, from each other. Dillw^n 

 seems to have been perfectly aware of this confusion, but, gene- 

 rally useful as his catalogue is, a resort to his numerous references 

 in this instance, will soon prove to the student whether he has 

 added to the obscurity or diminished it. It is to be hoped that 

 some one qualified for the task will undertake a monograph of the 

 genus. Lamarck has done a great deal ; but a great deal remains 

 to be done. 



I am not aware that any one has observed the labial tooth 

 which projects from the external lip of many of the Murkes. It 

 is very much developed in perfect specimens of M. radix, more 

 especially in those which come from Panama. I have seen it also 

 very much exserted in M. ramosus and other species. It may be 

 traseed at each stage of growth when it is well developed. M. 

 saocicola has it, but not so strongly marked as the shells above 

 mentioned. Its use, in our present state of ignorance of the habits 

 of the animal, we are left to conjecture. 



Art. XXII. On a new Genus oflguanidce. By Thomas 

 Bell, Esq. F.L.S. 



The multitude of new forms which are daily presenting them- 

 sekes to the observation of the Zoologist, and the consequently 

 improved knowledge we obtain of the affinities by which the 

 various groups of animals are connected, have gone far to establish 

 principles of classification, probably approaching to the grand 

 plan upon which the animated world was created. Still however 

 our knowledge of the natural arrangement must be confessed 

 to be as yet confined to a feeble glimmering of light, the first 

 bright line, as it were, of dawn, but gradually widening and 

 brightening, and rendering the prospect more and more distinct 

 and clear, with every additional ray that is poured upon it. Al- 

 though therefore numbers of those links which entered into the 

 construction of the original chain of nature, have doubtless been 

 irremediably lost, (here is yet reason (o anticipate that the 



