STALK-EYED CRUSTACEA 155 



Abdomen in the male seven-jointed ; its base usually 

 occupies the whole width of the sternum, between the fifth 

 pair of legs. 



Range. — Atlantic and Pacific Oceans ; in shallow and 

 deep water. 



Synopsis of the Species. 



A. Frontal lobes armed. 



c7. Spines on orbital border. 



a^. Spines on both borders, superior and inferior. 



1. Carapace with spines on hepatic regions. — (P. 

 aculcatus?) 



2. Carapace without spines on hepatic regions. — (P. 

 vinacciis^ 



3. The superior orbital border has among its spines 

 t wo large spines separated by a fissure ; antero-lateral 

 spines bifid. — (P. caribceiis.) 



b^. Spines on inferior orbital borders only. 



4. Inferior border has four spines. A row of long, 

 thin spines on walking legs.— (Z'. gracilipes.) 



B. Frontal lobes unarmed. 



b. No spines on orbital borders. 

 c^. Carapace smooth. 



5. Spines on walking legs. — (/^. lactciis.) 

 f'\ No spines on walking legs. 



6. Inferior orbital border with small granulations. — {P. 

 quoyi.) 



7. Inferior orbital border with many pointed granula- 

 tions. — (^P. miersii.) 



d^. Carapace with tubercles. 



8. Superior orbital border has two or three almost 

 spiniform tubercles. — {P. geuii/iatns.) 



9. Frontal and orbital borders a continuous line. — {P. 

 muiifrons.) 



