042 Mil, E. J. MIEES ON THE 



approximation of tlie Maioid to the Cancroid type through the 

 development of the orbits and of the basal portion of the antennae, 

 the increase in width of the interocular portion of the carapace, 

 the shortening of the epistome, and the obsolescence of the 

 rostrum. 



In the synoptical arrangement of the families, subfamilies, and 

 genera which follows, I have omitted all references to the litera- 

 ture, as these will, it is hoped, be given on a future occasion, and 

 the characters themselves are to be regarded as merely diagnostic. 

 Those genera which are unknown to me from examination of spe- 

 cimens are distinguished by an asterisk ; and it may be, as the 

 descriptions are often short and insufficient, that I have referred 

 one or two to a wrong position in the system. Synonyma are 

 placed in brackets and printed in italics. In every case I have cited 

 what I regard as the typical species of the genus. Many of the 

 genera are distinguished by characters of very trivial import- 

 ance ; and it is impossible in any linear arrangement to express 

 adequately their very complex affinities ; but is hoped that the 

 present arrangement, while on the whole a natural one, will serve 

 as a practical guide to the determination and classification of the 

 numerous types of this interesting group. 



Synoptical Aerangement oe the Families, Subfamilies, 

 AND Q-eneea. 



Family I. INACHIDiE. 



Eyes non-retractile, or retractile against the sides of the carapace. No 

 defined orhits exist ; but there is often a well-developed prseocular and 

 postocular spine. Basal joint of antennae usually slender, sometimes 

 moderately enlarged. 



The carapace varies in shape, being subtriangular, or oblong-triangular, or 

 subpjfriform. Rostrum simple or bifid, sometimes very short. An- 

 terior legs with the fingers never excavated at the tips. Ambulatory 

 legs sometimes very long. Postabdomen of male and female 4- 

 to 7-jointedj two or three of the joints often coalescent. 



Subfamily 1. Leptopodun^. (See Plate XII. figs. 1, 2.) {Macropo- 

 diens, M.-Edwards, part. ; Leptopodidce, Dana, part., Stimpson.) 



Eyes slender, non-retractile, and laterally projecting. Prreocular and 

 postocular spines minute or wanting. Basal antennal joint very slender 

 throughout its length. 



