PREFACE. op, 



correct account of the species belonging to liis 

 own country. 



It is proper to state here, that when the work 

 was nearly ready for publication the annexation 

 of the republic of Texas to the United States 

 enlarged the area of the author's investigations, 

 by the addition of a region of many thousand 

 square miles in extent to the vast territory already 

 included in the field of his inquiry. He endeav- 

 ored to meet the exigency by employing a com- 

 petent naturalist to explore the accessible parts 

 of that State during the early part of 1846 ; l)ut 

 it cannot be expected that the results of that ex- 

 ploration can exhibit more than an incomplete 

 view of the species living there. A wide field 

 of investigation is left for the future naturalist, 

 both in Texas and in the whole extensive and 

 but partially-explored region west of the Missis- 

 sippi river. 



The author takes pleasure in maldng this 

 public acknowledgment of his obligations to those 

 gentlemen who have kindly furnished him with 

 materials used in the preparation of the work. 

 To R. E. Grifiith, M. D., late of the University 

 of Virginia, a cotemporary of, and fellow-la])<)ror 



