480 Mr. L. A. Borradaile on the 



Key to the Families of the Oxyrhyncha. 



I. Carapace tliin and flat. First legs (chelipeds) 



not lon<? or specially mobile or with fingers 

 bent at an angle with the hand. Male 

 opening sternal. [No orbits. Second joint 

 of antennal stalk slender, fused with epistome 

 but not with frout. No hooked hairs.]. .. . HymenosomidaB. 

 II. Carapace not thin and flat (except Ocinopus). 

 First legs either mobile or powerful, with 

 bent fingers. Male opening coxal. 



A. Chelipeds specially mobile, rarely much 



greater than the other legs, or with fingers 

 bent at an angle on the hand. Second 

 joint of antenna well developed, generally 

 fused with epistome and often with front. 

 Orbits generally mf)re or less incomplete. 

 Hooked hairs almost always present .... Maiidaa. 



B. Chelipeds not spicially mobile, usually 



much longer and heavier than the other 

 legs, and with fingers bent on the hand 

 at an angle towards the side on which the 

 fixed finger is set. Second joint of an- 

 tennae small, short, and not fused with 

 epistome or front. Orbits well made. 

 Hooked hairs almost always wanting . . Parthenopidae. 



Key to the Suhfamilies of the Maiidse. 



1. Second j oint of antennae very slender through- 

 out its length. [No orbits. Eye-stalks 

 generally long.] InachincB. 



II. Second joint of antennae not very slender. 



A. No true orbits (eye-stalks hidden under a 



supraocular spine or sunken in the sides 

 of a great rostrum). Second joint of 

 antenna truncate-triangular. Eye-stalks 

 very short Acanthonychiiue. 



B. True orbits, containing both supra- and 



postocular elements sheltering the eyes, 

 are more or less completely formed, except 

 in a few genera where the eye-stalks are 

 long and slender. Second antenna-joint 

 broad, usually not truncate-triangular. 

 Eye-stalks long or short. 



1. A large, cupped, usually blunt postocular 



process present. Eye-stalks short. 

 Cornea of eyes not completely hidden 

 when they are folded back Pisince. 



2. Postocular process, if present, usually 



sharp and not cupped, but if not so, 

 then cornea hidden (as also in most 

 other cases). Eye-stalks usually long . Maiince. 



Key to the Suhfamilies of the Partlienopidse. 

 I. Carapace usually triangular, sometimes sub- 

 oval or subpentflgonal. Rostrum simple. 



