428. STALK-EYED CRUSTACEA 



margin with many long, spine-like teeth that interlock 

 when closed. The swimming organ has the outer plate 

 large and strong and the inner small ; the central plate 

 is quadrate. 



Range. — West Indies; in deep water. 



Group II. Normalia (Spence Bate). 



The gills are well developed. The abdomen is not 

 out of proportion with the rest of the body, cephalo-thorax 

 and abdomen being well developed. The segments more 

 or less overlap. 



Tribe I. Synaxidea. 

 Tribe II. Astacidea. 

 Tribe III. Stenopidea. 



Synopsis of the Tribes. 



A. The anterior pairs of legs have no pincers; the 

 legs are six-jointed. The external antennae have no scale 

 on basal joint. — [Synaxidea^ 



B. The anterior pairs of legs have pincers, the first 

 pair the largest ; the legs are seven-jointed. The basal 

 scale of external antennae is small or large. — {^Astacidea?) 



C. The anterior pairs of legs have pincers, the third 

 pair the largest; the legs are seven-jointed. There is 

 a basal scale on external antennae. — {Stenopidea.) 



Tribe I. Synaxidea. 



Synaxidea Spence Bate. 



The external antennae have no basal scale. The in 

 ternal antennae terminate in two flagella. The legs have 

 six joints, and have no pincers, except the last pair some- 

 times in the female. The ova are very small. 



