2 BEITISH COPEPODA. 



Baird's work, which must always take rank among the 

 classics of natural history. 



The number of species of non-parasitic Copepoda 

 noticed by Dr. Baird is thirteen, since which time 

 several species, both fresh- water and marine, have been 

 described by Sir John Lubbock, the Rev. Alfred 

 Merle Norman, the late H. Goodsir, and by myself 

 both singly and in conjunction with my friend, Mr. 

 David Robertson, of Glasgow. The species com- 

 prised in this Monograph will number, so far as at 

 present appears, one hundred and fifty-one. 



The truly parasitic forms fish-lice, &c., are ex- 

 cluded as not coming within the scope of my work. 

 They are of themselves sufficient to occupy an 

 independent volume, and to afford abundant work to 

 any naturalist whose time and opportunities allow of 

 his taking them in hand. 



The researches of recent German writers espe- 

 cially of Dr. Glaus on the physiology, minute 

 anatomy, and embryology of the Entomostraca, are so 

 full and exhaustive, that anything I could have said on 

 those subjects would have been a mere epitome of 

 what can be better studied in the works of those 

 authors. I have, therefore, in the following pages, 

 confined my descriptions to the external form, not 

 travelling into details of physiological anatomy except 

 so far as necessary for purposes of classification and 

 specific description.* 



I have not thought it needful to give exhaustive 



* I hope, however, in an introduction to the second volume, to give 

 a brief outline of the state of our knowledge on these subjects. 



