564 



ZOOLOGY 



SECT. 



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

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

 the anterior region of the head. 



Fio. 461. Lepas anatifera. A, the entire animal ; B, anatomy, ai, antennule ; c. carina 

 cd. cement-gland ; 1. digestive gland ; m. adductor muscle ; oil. oviduct ; ov. ovary ; p. (in B) 

 penis and (in 4) peduncle ; s. scutum ; t. tergum and testis ; vd. vas deferensr (From 

 Lang's Comparative Anatomy, after Darwin and Claus.) 



The Sessile Barnacles or Acorn-shells (Balanus) have no stalk 

 (Fig. 462), the head-region being short and broad. The scuta (s) 



ad 



sc 



QD WQ 



Fia. 462. Balanus. A, external view ; B, anatomy. a\. antennules ; ad. adductor muscle ; 

 m. muscles of scuta and terga ; o. edge of parapet ; ov. ovary ; ovi. oviduct ; s. scutum ; 

 apet ; t. tergum ; wo. female aperture. (From Lang's Comparative Anatomy, after 



