316 Dr. Lracu’s Arrangement of the Crustacea, $c. 
Mr. C. Prideaux sent me the young of this species from the Ply- 
mouth Sound. 
The fissure in the under part ofthe orbit is wide enough to ad- 
mit a knife; in the two following species the sides of the fissure 
touch each other. 
Spec. 3. Portunus emarginatus. 
P. test’ convexiore lineis abbreviatis e granulis compositis, den- 
tibus tribus utrinque: penultimo minore, fronte emarginato, 
manibus supra unidentatis, unguibus posticis acutis. 
. Portunus emarginatus. Leach, Edin. Encycl. vii. 390. 
Habitat ad Danmoniz littora, semel obvius. 
Mus. Nostr. ¢. | | 
Abdomen r&mın® latum, tenue ciliatum, angustius quam in 
P. Depuratore, articulo penultimo minus arcuato, ultimo an- 
gustiore, acutiore, secundo tertioque minus carinatis, quarto 
vix carinato. 
Spec. 4. Portunus arcuatus. 
P. testa convexiore lineis abbreviatis e granulis compositis, denti- 
bus utrinque tribus ; penultimo minore, fronte arcuato integro, 
manibus supra unidentatis, unguibus posticis acutis. 
Portunus arcuatus. Leach, Edin. Encycl. vii. 390. 
Teste fronte arcuato integro, a Portuno emarginato tantum dif- 
fert; forte varietas ? | | 
Habitat in Angli: mari rariüs. 
Mus. Sowerby, Leach. ¢. 
** Ungues postici ecostati; palporum geminorum eaternorum caulis 
interni articulus secundus ad latus internum emarginatus ; orbita 
interne sub antenne externe insertione imperfecta. 
Spec. 5. Portunus marmoreus. 
P. testä convexä obsolete tenu? granulata, utrinque dentibus quin- 
| que 
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