PREFACE. vii 



Many of the readers of this Monograph will probably be surprised to find some old 

 generic names reproduced, which have long been superseded by those of modern writers ; 

 but a sense of justice to such authors as Van Phelsum, Breynius, Klein, and Leske, has led 

 me to consult their original works, and restore the genera first described and figured by 

 them, but omitted from the treatises of later authors on the same subject. In the nomen- 

 clature of the Echinodermata, had I merely gone back to the time of Linnaeus, as suggested 

 by the committee of the British Association in their report made in 1842, 1 must necessarily 

 have excluded the important work by Breynius,* in which, for the first time, were proposed 

 seven well-described and accurately figured genera of Echinoidea, which, by some strange 

 oversight, were not adopted by his contemporaries, although they have reappeared under 

 new names in the works of later authors. On the principle of priority, therefore, I have 

 restored the original genera so clearly defined by Breynius, even although it may occasion 

 a temporary inconvenience in the names of some well-known forms of urchins. 



In every case, where practicable, the name of the author who either first recorded, 

 described, or figured the species, follows the specific name of the object, without the 

 addition of " Sp." adopted by some authors. By this mode justice is done to the original 

 author, and confusion avoided. The modern practice of inventing and changing generic 

 names, and appending to the old specific name that of the individual who has merely 

 changed a name, but discovered nothing, cannot be sufficiently discountenanced, as it 

 greatly increases the confusion arising from an already overloaded synonymy, and thereby 

 retards the real progress of the natural history sciences. 



The accurate determination of species, and their distribution in time and space, form 

 problems of the highest importance to the palaeontologist, as their true solution are the 

 only certain guides of the geologist in his investigations in the field, and his generalizations 

 in the study : for the classification of strata, the subdivision of rock groups, and the 

 boundary hues between different formations, are all points which are more or less affected 

 by the soundness of his conclusions. 



In determining the species of Echinodermata, therefore, the most careful comparison 

 has been made with the true type forms to which they are referred, and the extent of 

 the section in the description of the species, on the affinities and diff'erences exhibited by 

 each with other Foreign and British congeneric forms, will show how much care has been 

 taken to arrive at a correct determination. 



The range and stratigraphical position of the species described in this work has 

 occupied much time and attention, as many errors found in previous lists of Oolitic 

 Echinodermata required considerable research to correct ; for experience has taught me 

 that, unless the palaeontologist can verify for himself the statements of his collectors, he 

 win frequently be led into similar errors. In every instance, with the exception of 

 the Northamptonshire beds, which have been carefully noted by my friend the 



* De Echinis et Echinitis, sive Methodica Echinorum distribution e, Sciiediasma. Gedani, 1 732. 



