ZOOLOGY 



These facts have led me to treat the subject largely 

 from a morphological standpoint, touching but lightly on the 

 Histology, Embryology, and Natural History of the forms 

 described. More space has been, as a rule, devoted to those 

 animals which are regarded as intermediate between the larger 

 groups than to the more specialised members of the groups. 



Any system of classification is to some extent a matter of 

 personal judgment. I do not suppose that adopted here has 

 any finality, but I hope the tables given will be of use to the 

 student as expressing the results of the most recent research. 



In preparing the volume I have been much helped by 

 numerous friends, to whom my best thanks are due. Dr. 

 D. Sharp, Dr. Hickson, Mr. Beddard, Mr. J. J. Lister, Mr. 

 F. G. Sinclair, Mr. C. Warburton, and Mr. MacBride, have aU 

 given me the most generous assistance, and, above aU, I am 

 most deeply indebted to my friend Mr. S. F. Harmer, who has 

 in the most kind way read through the proof-sheets, and whose 

 careful revision has saved me from many errors. 



To the Delegates of the Clarendon Press I owe thanks 

 for permission to use Fig. 133, taken from EoUeston and 

 Jackson's Forms of Animal Life. Herr Fischer of Cassel has 

 kindly given me leave to use some reductions from the admir- 

 able diagrams of Professor Leuckart ; these occur in the 

 groups Echinodermata and Arthropoda, and are acknowledged 

 under each cut; similarly the firm of Wieweg and Son have been 

 good enough to allow me to use four figures taken from Vogt 

 and Yung's Lehrlmch der Prahtischen Vergleichenden Anato^nie. 

 I am also indebted to Messrs. Macmillan and Co. for their 

 kindness in allowing me to use Figs. 37, 89, and 90, all of 

 them taken from Professor Parker's Elementary Biology. 



AETHUE E. SHIPLEY. 



Christ's College, Cambridge, 

 March 1893. 



