PREFACE. 



It is now generally recognised that a certain acquaintance with actual specimens is necessary for 

 the proper understanding of Plants and Animals. By the practical study of representative forms, 

 exemplifying the leading modifications of plant and animal life, the student oLtains a basis of 

 distinctly observed fact with which to compare other forms, and round wliich to cluster the infor- 

 mation derived from books. 



The University of London has given practical shape to this idea by selecting a series of common 

 types which " each candidate must be prepared to examine microscopically, to dissect and to describe." 



In this Atlas, which is intended to serve as a guide to, and not as a substitute for, practical 

 work, drawings are given of the various points of importance exempliiied by each of these types, 

 to enable the student to make out the points for himself on the actual specimens. Experience 

 both as students and teachers has taught us, that in this constant appeal to the object itself, tlie 

 student is gi-eatly assisted by clear and accurate drawings. In the triple alliance, as it may be called, 

 of description, drawing, and object, is found the easiest, safest, and surest means of successful study. 



Not only is the Atlas a guide to practical work, but since it contains the results of that work 

 in a permanent form, a glance at the drawings with their accompanying description will serve as a 

 valuable refresher to tlie memory before going up for examination. 



Further, the Atlas may be used with any of the Text-books of Zoology or Botany in common 

 use, such as those of Huxley, Nicholson, Macalister, Sachs, M'Nab, etc., because equivalent terms 

 are noted in the text, and thus the language of the science is translated as it were into the different 

 dialects. 



The drawings belonging to each form represent the leading features in tlie history of its life. 

 The structure as a whole is first shown, then the details of the various parts by means of separate 

 drawings, and finally so much of the history of its development as is likely to be required. 



lu every case the types represented have been practically examined, and drawings made from 

 nature. A number of the drawings are taken from dissections and microscopic preparations made 

 in tlie Biological Laboratory of the Iloyal School of Mines, London. Others are copied from reliable 

 sources whenever they give clearly and correctly the most instructive view of the object. In the 

 development special care has been taken to give only such representations as were drawn by 

 practised observers, c.y. the development of the Amoeba is taken from Haeckel, and that of the Cray- 

 fish fi'om Eathke. 



Drawings after nature are headed Figures, and Diagrams are occasionally introduced for 

 explanatory purposes. 



The explanatory text arranges the information obtained from the drawing in a convenient form, 

 explains briefiy the nature of the object seen, states equivalent terms when the same thing is 

 differently named by standard authors, gives the derivation of names when that throws light on their 

 meaning, and accents them where there is any danger of wrong pronunciation, and finally sums up 

 the distinctive characters in the form of a classijicatimi. 



