PORTUNUS ARCUATUS. 
Fig . 5 — 6 . 
P. (#. b.) testa convexiore lineis abbreviate e granule composite, dentibus utrinque quinque 
penultimo minore; fronte arcuato integro; manibus supra uni-dentatis; unguibus posticis 
ciClltlS. 
Portunus arcuatus. Leach Edinb. Encycl. vii. 390. 
Trans. Linn. Soc. xi. 316. 
Fig. 5. Portunus arcuatus. 6. Maris abdomen. 
P. arcuatus differs from P. emarginatus only 
may be no more than a variety of that species. 
England. 
in the form of the anterior part of the shell, and 
It inhabits the northern and western coasts of 
