480 



THE VOYAGE OF H.M.S. CHALLENGES. 



Group NORMALIA. 



This group includes many genera that naturally fall into four tribes, and these 

 again into several families, each having distinguishing features that clearly define it 

 from the others. 



The three posterior pairs of pereiopoda, even in the females, are never chelate, 

 whereas the first two pairs generally are, although in the Pandalidee the first pair 

 is simple and the second only minutely chelate, and in the Haplopodea all are simple. 



The ova are carried by the females attached to the pleopoda, and the brephalos so 

 far as known appears in the Zoea stage, with few exceptions, and these are in the 

 Megalopa condition. 



Corresponding modifications take place in the different genera, which lead to their 

 being divided according to their external characters and structural conditions, as shown 

 in the following tabular arrangement : — 



NORMALIA - 



Tribe. 



Crangonidea, 



Polycarpidea, 



Family. 



CrANGONIDjE, 



NlKIDil, 



AlFHEIDjE, 



HlPPOLYTID^, 



EANDiLIDA. 



1 



Genus. 



Crangon, 

 Pontophilus. 

 Subinea. 

 Pontocaris. 



Brephalos. 

 Zoea. 



Glyplwcrcinyou, . Megalopa. 

 Nika. 



Athanas. 



Parathanas. 



Cheirothrix. 



Alpheus, 



Betseus. 



Paralpheus. 



Synalpheus. 



Platybema. 



Latreutes. 



Hippolyte, . 



Spirontocaris. 



Nauticaris. 



HetairiLS. 



Chorismus. 



Merhippolyte. 



Amphiplectus. 



HeterocarpibS. 

 Plesionika. 

 Nothocaris. 

 \ Pandalus. 

 Pandalopsis. 

 Cldorotocus. 

 Dorodotes. 



i 



( Zoea or 

 | Megalopa. 



Zoea. 



