494 



CIRRIPEDIA. 



body the future thoracic and abdominal region grows re- 

 latively in length. There also appear close to the sides of the 

 unpaired eye two conical bodies, which correspond with the 

 frontal sense organs of the Phyllopods. During their growth 

 the different larvae undergo changes varying greatly in degree. 



In Balanus the changes consist for the most part in the full 

 segmentation of the appendages and the growth and distinctness 



FIG. 231. NAUPLIUS LARVA OF LEPAS FASCICULARIS VIEWED FROM THE SIDE. 

 oc. eye ; At. i. antenna of first pair ; At. 2. antenna of second pair ; md. mandible ; 

 Ib. labrum ; an. anus; me. mesenteron; d.sp. dorsal spine; c.sp. caudal spine; 

 Vp. ventral spine ; Ih. lateral horns. 



of the dorsal shield, which forms a somewhat blunt triangular 

 plate, broadest in front, with the anterior horns very long, and 

 two short posterior spines. The tail also becomes produced into 

 a long spine. 



In Lepas fascicularis the changes in appearance of the 

 Nauplius, owing to a great spinous development on its shield, 

 are very considerable ; and, together with its enormous size, 

 render it a very remarkable form. Dohrn (No. 520), who was 

 the first to describe it, named it Archizosea gigas. 



