348 
Dr. Leach’s Arrangement of the Crustacea, ^c. 
SUDDIVISIO 4. 
AntenncB exteriores infra interiores inserts ; interiores setis tribus. 
Cauda lamella exteriore uiiipartit^. 
Gen. 19 . PALiEMON, Fahr., Latr., <^c. 
Astacus, Pe?m. 
Cancer, Linn. 
Pedes quatuor antici didactyli, pari antico rninore. Palpi pedi- 
foimes articulo ultimo penultimo brevdore. 
Spec. 1. Palcemon serratus. 
P. rostro ascendente supra 6 - 7 - aut 8 -dentato apice emargi- 
nato ; infra 4- 5- vel 6 -dentato. 
Astacus serratus. Penn. Brit. Zool. iv. 19 . pi. \Q. fig, 28 . 
Palaemon Squilla. Latr. Gen. Crust, et Insect, i. o 4 . 
Habitat in Mari Britannico. 
Spec. 2. Palcemon Squilla. 
P. rostro recto apice emarginato supra 7- aut 8 - infra 2 - vel 
3-dentato. 
Cancer Squilla. Linn. Syst. Nat. i. 1051. 
Habitat cum prsecedente in Danmonia australi vulgate. 
Linnagus, in the second edition of Fauna Suecica, thus describes 
the above species: “ Thorace laevi rostro supra serrato ; subtus 
3-dentato, rnanuum digitis aequalibus.” — “ Rostrum lanceolatum 
perpendiculare, acutum, supra octo-crenis, infra tribus serratum ; 
inanus, quae tertio pedum pari insident, digitis sunt tequalibus.” 
In the last edition of Systema Naturce this character is again re- 
peated ; and as it applies exactly to the most frequent variety of 
this species, there cannot be the least doubt as to the correct- 
ness 
