DESCRIPTION OF PLATES, 29, 30. 671 



Fig. 10, (/) (</), second and third, biramous natatory legs (homologically 



the third and fourth thoracic limbs.) 

 (h), posterior point of carapace. 



(i), forked terminal projection of the body or abdomen. 

 (I), second forked projection. 

 (m), two sharp points, apparently representing a third forked 



projection. 

 (n) t a rounded swelling, apparently lying between the carapace 



and the supposed abdomen, and believed to form the 



anus. 



PLATE 30. 



Lakv^ of Lepas : SECOND and last stages of development. 



Fig. 1, Larva of Lepas in the second stage of development; «, sup- 

 posed antennae (second pair) ; m, mouth ; c, three pairs of 

 legs. (Copied from Burmeister's ' Naturgeschichte der Ran- 

 kenfiisser,' Tab. 1, fig. 3.) 

 2, Lepas australis : pupa or larva (2 a, of natural size) in the last 

 stage of development, with the young cirripede in its na- 

 tural position, obscurely seen within, — the specimen 

 having been treated with caustic potash, and so rendered 

 transparent, — viewed laterally and greatly enlarged. 

 Scarcely more than the outline of the shell or carapace is 

 represented. The darkly shaded part to the left repre- 

 sents the extent of the sack of the pupa, or the cavity occu- 

 pied by the thorax, with its limbs. 



a, both antennae, adhering by their discs to a piece of wood. 



b, dorsal surface of the shell or carapace ; and immediately un- 



derneath this letter is the point of reflection of the mem- 

 brane investing the thorax, so as to line the sack of the pupa. 

 b', is the posterior end of the animal, and of the orifice on the 

 ventral surface, through which the legs are protruded. 



c, six pairs of natatory legs. 



d, pair of caudal appendages, seated on a minute abdomen. 



m, mouth, from which the oesophagus can be seen running into 

 the stomach, the latter having two dark caeca ; the sto- 

 mach sweeps round in the pupa to the abdomen, near V ; 

 but in the young included cirripede, only as far as the 

 letter (b), where the bases-of the posterior pair of cirri and 

 the anus lie. 



n y apodemes, supporting the eyes, produced deeply inwards 

 from the eye-bearing segment (n, in fig. 4) of the antennae. 



s, bottom of sack of the young cirripede immediately after its 

 metamorphosis ; it extends as far as s'. (See s, in fig. 3.) 



t, gut-formed cement-gland (or incipient ovaria), seen on the 

 near side of the animal, whence a cement-duct, t', runs 

 into the near antenna. 



u t internal and anterior part of the pupa, filled with pulpy, oily 

 matter, together with the incipient muscles of the pedun- 

 cle ; when stretched out it forms the peduncle of the 

 young cirripede. See u' t in fig. 3. 



