8 STALK-EYED CRUSTACEA 



B. Basal joint of external antennae slender, not 

 narrowing distally. 



b. Eyes slender and retractile ; praeocular spine usually 

 wanting, postocular spine distinct. 



b^. Carapace triangular or subpyriform. 



b'^. The fourth joint of the external maxillipedes 

 truncated, or elongated and rounded distally ; the fifth 

 joint articulates with it at its antero-internal angle. 



b^. The first pair of legs of the male small, or has the 

 palm inflated and the fingers acute. Walking legs usually 

 slender, and often very long. — {InachhicB.) 



II. Basal joint of the external antennre enlarged. 



C. Basal joint of external antennae enlarged at base, 

 narrowing distally. 



c. Eyes small and immobile, or partially retractile ; 

 praeocular spine prominent, postocular spine minute or 

 wanting. 



c^. Carapace oblong and flattened, or elongate and sub- 

 cylindrical or subtriangular. 



c". The fourth joint of the external maxillipedes is 

 truncated distally; the fifth articulates with it at its 

 antero-internal angle. 



c^. The first pair of legs in the male usually has the 

 hands compressed. Walking legs of moderate length. — 

 (^AcantJionychincB^ 



D. Basal joint of external antennae enlarged through- 

 out its length. 



d. Eyes short and completely retractile ; praeocular 

 spine short or absent, postocular spine large. 



dy. Carapace triangular. 



d'^-. The fourth joint of external maxillipedes cordiform 

 or truncated distally ; the fifth joint articulates with it at 

 its antero-internal ancfle. 



