THE CEPHALOTHORAX. 151 



pleurobranchia (fig. 4, plb. 14) is attached; and in 

 front of this, it is connected, by a narrow neck, with 

 an elongated triangular piece, which takes a vertical 

 direction, and lies in the fold which separates the posterior 

 thoracic somite from the next in front. The base of this 



t.icv. 



Fig. 38. — Asfacnx fm'iatUl'^. — The mode of connexion hetween the last 

 thoracic and the first abdominal somites ( x 3). a, L-shaped bar ; 

 cpe, carapace ; rcrp. I4, coxopodite of the last ambulatory leg ; jM., 

 place of attachment of the pleurobranchia ; st. A V, sternum, and 

 t. XV, tergum of the first abdominal somite. 



piece unites with the ei:>imeron of the penultimate somite. 

 Its apex is connected with the anterior end of the horizontal 

 arm of an L-shaped calcified bar (fig. 38, a), the upper end 

 of the vertical arm of which is firmh^, but moveabh', con- 

 nected with the anterior nnd lateral edge of the tergum 

 of the first abdominal somite (^ XV.), The tendon of one 



