172 



STALK-EYED CRUSTACEA 



Neptutius 



Synopsis of the Genera. 



I. Lateral epibranchial spine the largest of the antero- 

 lateral marginal series of teeth ; preceding 

 teeth subequal. 



A. The flagellum of the external an- 

 tennae occupies the interior orbital hiatus. 



a. The abdomen of the male is more or 

 less triangular ; the epistome doe^ not pro- 

 ject in front so as to be visible on a dorsal 

 \\&\\ .—i^Ncptunns?) 



b. The abdomen of the male has a 

 broad base, then suddenly becomes thin, 

 terminating in a narrow lancet - shaped 

 point ; the epistome projects in front and 

 is visible on a dorsal view. — {Callinectes.) 



B. The flagellum of the external antennae 

 is excluded from thei nterior orbital hiatus 

 by a process of the basal antennal joint. 



c. The fourth joint of the external maxilli- 

 pedes is rounded anteriorly, and exceeds the 

 front ; its terminal joints are flattened. — {Lupa.) Lupa. 



Calliiiccies. 



II. The antero-lateral marginal series of teeth 

 are alternately large and small. 



d. The fourth joint of the external maxilli- 

 pedes is dilated externally and does not exceed 

 the front ; its terminal joints are cylindrical. — 

 {Croniits.) 



Croiiiiis. 



I. The lateral epibranchial spine is the largest of the 

 antero-lateral marginal scries of teeth. 



./. The flagellum of the extoiial anteninc occupies the 

 interior orbital hiatus : — 



