578 



ZOOLOGY 



SECT. 



bivalved carapace, formed by a fold of the skin, and strengthened 

 by five calcareous plates. Of these one is median and dorsal, and 

 is called the carina (c) ; two are lateral and proximal, the scuta (s)\ 

 and two lateral and distal, the terga (t). During life the carapace 

 is partly open, and from the ventrally placed aperture delicate 

 setose filaments are protruded and keep up a constant grasping 

 movement : these are the endo- and exopodites of the biramous 

 thoracic feet, of which there are six pairs. Removal of the carapace 

 shows the feet to arise from a vermiform unsegmented body 

 (B), attached on the ventral aspect to the stalk and carapace by 



l- 



B 



S. 

 jn - 



J-. 



c' 



FK; 454 Lepas anatifera. A, the entire animal; B, anatomy. 1; antennule ; c. carina : 

 cd. cement-gland ; /. digestive gland ; i. adductor muscle ; od. oviduct ; ov. ovary ; p. (in B) 

 penis and (in A) peduncle ; s. scutum ; t. tergum and testis ; vd. vas deferens. (From Lang s 

 Anatomy, after Darwin and Claus.) 



its anterior end, while its posterior end is free and terminates in 

 a long filament, the penis (p), immediately dorsal to which is the 

 anus. The mouth is ventral and anterior, and is provided with 

 a pair of mandibles and two pairs of maxillae. There are no 

 antennae: at first sight the antennules appear to be absent, but 

 a careful examination shows the presence of a pair of minute 

 structures (a) on the proximal or attached surface of the stalk, 

 and embedded in the cement by which the animal is fixed to its 

 support ; these are the antennules, and their position relatively to 

 the mandibles shows that the stalk is formed by an elongation of 

 the anterior region of the head. 



