672 DESCRIPTION OF PLATE, 30. 



x, bases of the pedicels of the cirri of the young included 

 cirripede. 

 Fig. 2 a, Pupa of Lepas australis of natural average size, within a half- 

 inch wide. 



3, Young cirripede (on a smaller scale than Fig. 2), immediately 



after the exuviation of the bivalve-like pupal carapace, the 

 basal segments of the antennae, the eye-apodemes and eyes. 

 The young cirripede has just assumed its proper position 

 at nearly right angles to what it held whilst packed within 

 the pupa, — this change of position having been effected by 

 the opening out or stretching of the deep fold of mem- 

 brane (see n, in fig. 2) formed over the eye-apodemes and 

 eyes, previous to the act of exuviation. 



a, the three terminal segments of the antennae of the pupa, still 



remaining cemented, in the same position as before, to the 

 same piece of wood : the basal, or eye-bearing segment (n, 

 in fig. 4), has been moulted with the pupal carapace. 



c, d, legs and caudal appendages of the pupa, not as yet moulted, 

 but quite functionless ; the external membrane of the 

 thorax, and that lining the sack of the pupa, are, likewise, 

 as vet retained, but soon will be cast off. 



s, bottom of the sack of the young cirripede, which can now be 

 easily distinguished. 



u' t the peduncle. 



x, y, z, primordial valves, composed of chitine : x, being the 

 scutum ; y, the tergum ; z, the carina. 

 3 a, small portion of one of the primordial, non-calcified valves, 

 much magnified. 



4, ventral surface of pupa ; on the same scale, aud in the same 



semi-transparent condition as in fig. 2. 

 «, antennae. 



b, limit of sack on the sides in the ventral or lower half of the 



pupa. 

 b', posterior end of the carapace. 



c, d, bristles of the natatory legs and of the caudal appendages, 



protruded through the orifice of the carapace. 

 e, orifice of the acoustic sacks. 

 m s mouth, with the oesophagus attached to it, obscurely seen 



through the carapace ; the stomach having been removed. 

 n, apodemes supporting the eyes. 

 n, the eye-bearing or basal segments of the antennae. 

 o, the second or main segment of the antennae. 

 p, the third or disc segment of the antennae. 

 v, the fourth or terminal segment of the antennae. 

 W, ventral surface, bordered by the edges of the carapace ; the 



letter stands near the extremity of the oesophagus. 



5, First pair of natatory legs : /, lower segment of pedicel ; g, 



upper segment of pedicel ; h, lower segment of ramus ; 

 t, upper segment of ramus ; k, outer ramus ; /, inner 

 ramus of same leg; r, sternal surface between the first and 

 second pairs of legs, with singular thickened ridges and folds. 



