314 Mr. A. Hancock on a BwTowing Barnacle. 



surface : the four arms or feet next the mouth provided each 

 with a prehensile cushion : palpi furnished with pincers ; upper 

 lip rostrated. 



A. lampas. Animal with the margins of the lips thickened, 

 each being furnished posteriorly with a curved point or process ; 

 posterior portion considerably depressed, rounded, and provided 

 with a horny plate on the upper surface : chamber in the shell 

 of mollusks, partially lined with calcareous matter secreted by 

 the animal; opening narrow, enlarged and rounded in front, 

 tapering and curved behind. Length y\ths of an inch, breadth 

 y^gths of an inch. 



EXPLANATION OF PLATES VIIL and IX. 

 Plate VIIL 



Fig. 1. A portion of Fusus antlquus exhibiting numerous specimens of 

 Alcippe lampas in the columella and sides of whorls : a, stain 

 caused by the animal ; h, slit by which it communicates with the 

 water. 



Fig. 2. Much-enlarged view of the external appearance of the chamber of 

 Alcippe lampas : a, stain produced by the animal seen through the 

 shell, exhibiting pale radiating lines and punctures ; b, slit in the 

 matrix or shell by which the animal communicates with the water ; 

 c, calcareous layer partially lining the chamber, and projecting 

 beyond the margins of the slit ; d, calcareous granules filling up 

 posterior extremity of ditto. 



Fig. 3. Upper view of Alcippe lampas removed from its chamber : a, ante- 

 rior portion containing the arms and true body ; b, broad disc-like 

 portion corresponding to the pedicle of the pedunculate Barnacles; 

 c, valvular lips ; c', the slit or opening; d, posterior terminal points 

 of lips ; e, horny plate ; /, arms partially exserted ; g, the point at 

 which the animal is attached to the chamber. 



Figs. 4, 5. Under and side views of the same : letters as in fig. 3. 



Fig. 6. Anterior portion laid open to show the true body and arms : a, one 

 of the valvular lips ; b, the other cut across and laid back ; c, fleshy 

 pedicle supporting the arms d ; e, mouth ; /, upper lip ; y, rostrated 

 termination of same; h, arms or palpi by the sides of the mouth 

 furnished with pincers ; i, branchiae. 



Fig. 7. Portion of the true body as seen in the compressor: a, upper lip ; 

 b, rostrated termination of same ; c, carinated margin of same ; 

 d d, arms or palps by sides of mouth ; e, prehensile arms ; e', the 

 mouth ; /, the outer or first pair of mandibles ; g, second pair of 

 ditto ; h, third or innermost pair of ditto ; i, the branchice. 



Fig. 8. A few of the plates or setae of the branchiae highly magnified, ex- 

 hibiting a double channel at the broad extremity which is bifid. 



Fig. 9. Prehensile cushion of the arms. 



Plate IX. 



Fig. 1 . The prehensile arms highly magnified : a, fleshy pedicle; b b, cushion- 

 like swelling of same. 



Figs, 2, 3; 4. Different views of the larva of Alcippe lampas : a, interrupted 

 rose-coloured line surrounding the dorsal shield. 



Fig. 5. A mass of the eggs a little magnified. 



Figs. 6, 7, 8, 9, 10. Eggs highly magnified, exhibiting different stages of 

 development. 



