INTRODUCTION 



hi these days of nature study in the schools and elsewhere, atten- 

 tion is chiefly paid to a few striking- groups, the birds apparently 

 being the forms most favored. Invertebrates with the exception 

 of mollusks and insects, are receiving very little attention, though 

 there is a wealth of material awaiting the patient inver.tigation of 

 their life histories and habits. 



One of the evident reasons for this is the lack of facilities for 

 easily identifying the forms collected. The literature of the subject 

 is large, though much of it consists of mere verbal description, 

 and only a part of the species have been figured. INIuch of it too, 

 is usually inaccessible except to those within reach of large libraries. 



The group of which the present catalogue treats, the malacos- 

 tracous Crustacea, perhaps suffers less from this deficiency than 

 some others, for many of the forms are large and conspicuous and 

 have been frequently brought to public notice. It is true also that 

 keys to the greater part of this group have been recently published, 

 but it is the belief of the writer that, even with the best of keys, 

 the inexperienced observer has difficulty in identifying members of 

 large groups without the aid of illustration. 



It is with the hope of partly remedying this deficiency that this 

 catalogue has been prepared, and figures of all the species taken 

 within the city limits are here given. It is not complete ; the 

 collecting has not yet been extensive enough to include all the forms 

 that occur. Still over 60 species have been taken, either within the 

 city limits or at localities near by where the conditions are sufficientlv 

 similar to warrant the certainty that they will be found within the 

 area under discussion. 



Descriptions of the species have been made as brief as practicable 

 and only the most salient and characteristic marks given. In the 

 Decapoda, where the families are represented by but one or two 

 genera, the diagnosis of the family has been omitted, that of the 

 tribe being thought sufficient. In the Arthrostraca, on the other 

 hand, short diagnoses of the families represented have been 

 presented. 



