SCOPE 3 



It is hardly necessary to mention that if two page numbers occur after a word in the Index, 

 as in 



Acoela, 1 3, 22 



the Acoela will be found on both pages. This is because Acoela is an order within the class 

 Turbellaria (phylum Platyhelminthes) and within the class Gastropoda (phylum Mollusca). 

 I referred on page 2 to the inclusion in the Index of animals mentioned in a number 

 of textbooks of physiology and biochemistry. The format of this book prevents all of these 

 being referred to in the text, even if this were desirable, and a number have, therefore, been 

 mentioned only in the Index. In such cases the entry is of the form 



*Eiiocheir, Reptantia, 31 



The entry shows to which sub-order Eriocheir belongs, while reference to p. 31 shows that 

 Eriocheir is a crustacean and not a mollusc.^ If, therefore, a reader wants to look up a particu- 

 lar genus in this book, reference must, in the first instance, be made to the Index and not to 

 the text, as more animals are mentioned in the former than the latter. No English names are 

 given of genera which are only mentioned in the Index. 



All the classifications have been discussed with specialists on the group or groups in 

 question. To avoid cluttering up this chapter with innumerable acknowledgements to the 

 many scientists who have had the kindness and patience to help me, an Acknowledgement 

 Appendix is included at the end of this book. In fairness to those who have helped me, I should 

 own that I have not always taken their advice. Any errors^ are, therefore, my responsibility 

 and due to ignorance of a diverting branch of natural science which is neglected by many 

 'modern' biologists. 



Since my book is, in a sense, a dictionary, I will conclude this chapter with some observa- 

 tions made by a previous lexicographer (Johnson, 1755, AJ). 



'It is the fate of those who toil at the lower employments of Hfe, to be rather driven by the 

 fear of evil, than attracted by the prospect of good ; to be exposed to censure, without hope of 

 praise ; to be disgraced by miscarriage, or punished for neglect, where success would have 

 been without applause, and diligence without reward. 



'Among these unhappy mortals is the writer of dictionaries; whom mankind have con- 

 sidered, not as the pupil, but the slave of science, the pionier of literature, doomed only to 

 remove rubbish and clear obstructions from the paths of Learning and Genius, who press 

 forward to conquest and glory, without bestowing a smile on the humble drudge that 

 facilitates their progress. Every other authour may aspire to praise; the lexicographer can only 

 hope to escape reproach, and even this negative recompense has been yet granted to very few.' 



' Reptantia Is a sub-order of Decapoda (Crustacea); but Decapoda is also a sub-order of Dibranchia 

 (Mollusca). 



- This book is certain to contain errors and misprints. I should be most grateful if readers would let mc 

 know when they detect them. 



