DECAPOD A . LEPTOPODIA DM. 



BRACHYURA. 



GENUS ACH^US, LEACH. 



A(H.v:i >, Leach, Latr. Edwards. 



Generic character. External antennae remote, setaceous, the 

 first articulation united to the front, and extending beyond the 

 inner canthus of the orbits ; the second articulation inserted at the 

 side of the rostrum, and entirely exposed from above, and, with 

 the third, much thicker than the subsequent ones. External pedi- 

 palps, with the second articulation much longer than broad, and 

 produced at the interior and anterior angles, the third subtriangular 

 with the angles rounded. The first pair of feet (in the female) 

 short, rather slender; the second and third pairs having the ter- 

 minal joint long and styliform ; that of the fourth and fifth com- 

 pressed, abruptly curved, and falciform. Carapace somewhat tri- 

 angular, slightly spinous, the branchial regions elevated and swollen. 

 Hostrum extremely small, bifid. Eyes not retractile, placed on 

 long footstalks of equal size, and furnished with a single tubercle 

 on the fore-part. Abdomen six-jointed in both sexes. 



This genus, of which one species only is at present 

 known, is considered by Dr. Leach as intermediate between 

 Inaclius and Leptopodia \Macropodia\, and by Milne Ed- 

 wards it is placed between Stenorynchus (Macropodia Le.) 

 and Camposcia. Its relation to Eurypodius is also pro- 

 bable from the character of the feet, whilst the structure of 

 the eyes and some other points appear to indicate an ap- 

 proach to some of the Maiadce. 



