DEC A POD A . PEN MA DM. 



MACROURA. 



GENUS PEN^US. FABB. 



PAL^MON. Oliv. 



PKN^EUS. Fabr. Bosc. Latr. Leach, Edw. 



Generic character. External antennae about as long as the 

 body, the scale slightly decreasing and rounded at the apex, ciliated 

 on the inner margin. Internal antennae with the first articulation 

 very broad, hollowed above, forming a cavity for the eyes ; the 

 outer margin armed with a tooth, and the inner furnished with a 

 lamellar and ciliated appendage ; the last two joints very short. 

 The filaments of these antennae are double and generally very short. 

 External pedipalps long, slender, and pediform, furnished at their 

 base with a long, curved, ciliated appendage. Feet all with a small 

 appendage at the base ; the first three pairs didactyle, increasing 

 in length from the first to the third. Carapace with a prominent 

 median crest, extending into a long toothed rostrum. Eyes very 

 large and round. Abdomen large and much compressed ; its pos- 

 terior half carinated. False feet much enclosed by the lateral 

 portions of the abdomen, terminating in two unequal ciliated 

 plates. 



One species only of this genus has been found on our 

 coasts. 



