248 melampinjE. 



Species of Leuconia. 



alba, Walk. occideutalis, Pfoif. 



bidentata, Mont. Sayi, Kiist. 



Bivonae, Phil. succinea, Pfeiff. 

 Michelii, Mittre. 



Genus PEDIPES, Adanson. 



Foot divided inferiorly by a transverse groove. 



Shell sub-globose, imperforate, transversely striated ; spire 

 short, obtuse ; aperture narrow ; inner lip flattened, exca- 

 vated, with three plaits, the posterior the largest ; outer lip 

 posteriorly sinuated, with two teeth internally ; margin 

 acute. 



Ex. P. afer, Gmelin,^!. 83, fig. 4, 4. a. Shell, P. afer, 

 fig. 4, b. 



When the Pedipes walks, the hind part of the foot is 

 fixed, and the fore part, which is separated from the hind 

 part by an extensible groove, is advanced, and the hind half 

 is then drawn forwards so as to touch the anterior half, and 

 so progression is effected by a series of little steps. This 

 movement, similar to that of the geometric or looping 

 caterpillars, is executed with such quickness that few Mol- 

 lusks, according to Adanson, excel the Pedipes in alertness. 

 The animal lives in cavities of rocks, more especially of 

 those exposed to the sea ; Lowe also found it under stones 

 upon the sea-beach in Madeira. Species of Pedipes have 

 been detected in Africa, South America, and the West 

 Indies. 



