POTAMOBIUS. 
CANCER, Linnceus. 
ASTACUS, Fabricius. 
POTAMOBIUS, Leach. 
Antenna: externa: elougatae, subtus et extus internas insert®, pedunculo crasso, articulis secundo 
et tertio subcylindricis, squama mobili tectis. 
Antennce internee setis duabus ciliatis. 
Pedipalpi externi articulo secundo latissimo, crasso. 
Pedum par primum fere sequale, tumidum, carpo brevi, rotundo, manu leviter tuberculatum ; paria 
secundum et tertium attenuata, didactyla ; paria quartum et quintum monodactyla. 
Testa medio sulco transverso profundo subdivisa ; rostrum breve, trigonum utrinque unidentatum. 
Abdomen quinque-articulatum, lseve. 
Cauda pentapbvla, segmento primo-mediani utrinque unidentato. 
External antennae long, inserted below and outside the internal, with thick peduncle, second 
and third joints cylindrical, covered by a moveable scale. Internal antennae with two ciliated 
filaments. External pedipalps with second joint very broad and thick. Carapace divided in the 
middle by a deep transverse groove. Rostrum short, trigonal, single-toothed at each side. First 
pair of feet nearly equal, large, thick; wrist short, rounded; hand slightly tuberculated ; second 
and third pairs attenuated, two-fingered ; fourth and fifth pairs single-fingered. Abdomen with 
five joints, smooth. Tail w T ith five flaps ; first section of the middle flap with a strong tooth on 
each side. 
POTAMOBIUS ASTACUS. 
Tab. XXXIV. Fig. 1. 
p. testa granulate, rostro pedunculum antennarum longitudine aequanti, medio carinato, utrinque 
dente parvo versus extremitatem armato. 
Cancer astacus. Linnceus, 
B 
