IV 



In the Preparatory Notes of the first edition of this Catalogue, 

 published in 1886, tables were given to supply the number of species 

 described in H. Milne Edwards's Histoire des Crustaces, 1834 4> 

 as known to him from the whole world, and also of those then 

 known from the restricted area of my own collection. In a third 

 column was shown the number of species described up to 1886 

 from the restricted area ; while a fourth gave the number of 

 forms at that time in my collection. These columns are reproduced 

 below; and two others have been added enumerating, first, the species 

 now known, and, secondly, those now in my collection. The column 

 which gives the number of species described up to the present 

 time cannot be absolutely accurate, since some such species must 

 have escaped my notice ; nor is the number as large as it might 

 have been made, because many forms, which have been so 

 imperfectly described that it is to be feared they can never be 

 recognized, have been altogether omitted ; among these are a 

 considerable portion of the Crustacea described by the late M. Hesse. 



The growth of our knowledge of the Crustacean Fauna during 

 the last nineteen years has been simply astounding. In 1886 I 

 wrote and I felt that I was bold in doing so " I venture to 

 prophesy that, when the Crustacean Fauna of the Arctic and 

 Temperate Regions shall have been thoroughly investigated, it 

 will hereafter be found to embrace not less than 5000 species." 

 Now at the expiration of only nineteen years the number of known 

 species has actually risen from 3,209 to 5,435 ! 



I wrote then as an argument for what might seem to others 

 to be a presumptuous prophecy, that ** we know little of the 

 Amphipoda of the Western Atlantic and nothing of the free living 

 Copepoda and other smaller Crustacea of that district, and very 

 little of those of some other parts of the area." At the present 

 moment, notwithstanding the vast recent additions to the Fauna, 

 that statement is as true as it was then, for the discoveries which 

 have been made have been for the most part from the depths and 

 surface of the ocean, and from those portions of sea and land 

 which had previously been the most efficiently investigated. More- 

 over, as yet we know very little of the Harpactoida and other 

 groups of smaller Crustacea of the Southern portions of the area, 

 including the Mediterranean and Azores, while depths from fifty 

 fathoms down to the great abyss of the ocean still hide a Crustacean 

 wealth of small species, the existence of which we are only just 

 beginning to realize. 



