.median flagellum 



scaphocerl te 



(antennal 



scale) 



.lateral flagellum 



med 

 promin 



^3rd antennular segment 



.2nd antennular segment 

 _distolateral spine 



;>; i_lst antennular segment 

 ^ prosartema 



1 



_stylocerlte 



a 



pocerlte 

 antennal 

 egment) 



segment) 



Figure 2. — Cephalic api')endaKes and eye of a member of the genus Penaciis. a. Dorsal vle«- of right antennule. b. 'N'entro- 



lateral view of right antenna, e. Dorsal view of right eye. 



adjacent adrostral carina. He also called attention 

 to another character, a well-defined hepatic carina. 

 Kubo grouped the nongrooved Penaeu-s; Division 

 1, into two subdivisions, characterized by the pres- 

 ence or absence of a hepatic carina, the depth of 

 the adrostral sulcus, and the development of the 

 adrostral carina. 



I consider that within the genus Penaeu.s are 

 four different groups which are here designated as 

 subgenera. 



Key to the Subgenera of the Genus 

 penaeijs 



1. Adrostral sulcus and carina short, not reach- 

 ing posteriorly beyond midlength of cara- 

 pace; gastrofrontal carina absent 2 



Adrostral sulcus and carina long, reaching pos- 

 teriorly much beyond midlength, usually al- 

 most to posterior margin of carapace ; gastro- 

 frontal carina present MeJicerhis 



464 



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