1 882.] Recent Literature. 66y 



Our western and southern streams and wayside ditches or runs 

 abound in these creatures ; such is C wib h u.s , /./, [<ii i Fig. i). With 



hand, the student should read this book, identifying all the parts 

 which can be observed without dissection, and then he should 

 verify for himself Professor Huxley's account of its internal 

 anatomy, and then if possible obtain from his own examination 

 some idea of its histology and its mode of development. Then 

 his studies should be comparative. He should, if possible, ex- 



hrimps. He should then 



i tnent of the crayfish with 



that of the Penasus (Fig. 3.), a prawn whose developmental his- 

 tory throws so much light on the ancestry of ail the higher Crus- 

 tacea, since its development is, in a sense, an epitome of that of 

 the Crustacea as a class, for it begins life as a little six-legged 

 Nauplius, then assumes the zoea phase of most crabs and shrimps, 

 and finally passes into a prawn. Then, with this excellent guide 

 in hand, he should study as well as may be, the fossil allies of 



