G40 MK. E. J. MIERS ON THE 



Within the Maiinca, a regular gradation of characters may be 

 traced from tlie forms {LeptopocUa and Stenorliynchus) with non- 

 retractile and laterally projecting eyes and narrow basal* autennal 

 joint and elongated epistoma, at one end of the series, to those 

 (exemplified in Pericera and Mithrax) with deep circular and 

 well-defined orbits, transverse epistoma, and greatly developed 

 basal antennal joint, at the other ; and I accordingly distinguish 

 among the Maiinea three principal groups, founded upon the 

 orbital and antennal characters, as will be seen in the following 

 tabular arrangement. 



Legion I. Maiinea. {Maiinea, Dana; InacJididiens, A. M. -Edwards.) 

 Basal antennal joint well developed, inserted beneath the eyes, and 

 occupying a great part of the infraocular space. 



Family I. Inachid^. Eyes non-retractile, or retractile against the 

 sides of the carapace. No defined orbits exist ; but there is often a well- 

 developed presocular or postocular spine. Basal joint of antennae usually 

 very slender, sometimes moderately enlarged. 



Family II. Maiid.e. Eyes retractile within the projecting orbits, which 

 are more or less incomplete below the eyes, or marked with open fissures 

 in their upper or lower margins. Basal antennal joint always more 

 or less enlarged. 



Family III, Pericerid/e. Eyes usually retractile within the orbits, 

 which are small, deep, and circular, never incomplete. Basal antennal 

 joint well-developed, and usually very considerably enlarged. 



As a rule, there can be no difficulty in assigning to any genus 



its place in one or other of the three families characterized above ; 



yet, as the Maiidse constitute a group intermediate between the 



Inachida3 and PericeridjB, there are certain genera which lie on 



the border line separating the Inachidse and Maiidse, whicli 



might be referred with almost equal justice to either family unless 



some artificial limit w^ere imposed. In LoxorhyncTius, for example, 



the prseocular and postocular spines and basal antennal joint are 



largely developed, and this genus approximates closely in its 



orbital and antennal characters to I^isa and its allies among the 



Maiiuse; and, to take another instance, Tyclie has its upper orbital 



margin as much developed as Acantlioplirys among the Maiidse, 



yet cannot be separated from its natural allies Stenocio7iops and 



StillognatTius, which belong to the Inachidse. Again, among the 



Maiinea with deflexed front, it will be shown that a regular transi- 



* I use this term, in the sense commonly employed by authors, for the large 

 joint which is apparently tlie first of the basal portion of the antenna), but is 

 in reality the second joint ("basicerite'"). 



