THE C1RR1PEDIA 



125 



shell. A deep fold of the integument (y) is formed on the ventral 

 surface of the preoral region. At the next moult this fold becomes 

 opened out, and the ventral surface posterior to it, which was at 

 first in contact with the surface of attachment, becomes erected at 

 right angles to this surface (Fig. 75, C). In this way the peculiar 

 form of body characteristic of the adult Cirri pede is attained. In 

 the Pedunculata the stalk is developed by the elongation of the 

 preoral region of the head. The compound eyes are cast off with 

 the Cypris cuticle, and the rudiments of the five primary valves of 

 the shell (scuta, terga, and carina) are developed. 



Diagram illustrating the metamorphosis of Lepas. A, Cypris stage. B, attached larva. C, 

 young Lepti.-t, still surrounded by the loosened Cypris shell (*). <>.', antennule ; ab, abdomen ; 

 c, carina ; rf, alimentary canal ; m, mouth ; o, nauplius-eye ; pa, paired eye ; r/, thoracic limbs ; 

 .s-, Cyprlt shell ; sc, scutum ; t, tergum ; x, dorsal fold ; ?/, ventral fold. (From Korschelt and 

 Heider's Embryology.) 



MORPHOLOGY OF ASCOTHORACICA. 



In the Ascothoracica, all of which are parasitic in Zoantharia 

 or Echinoderma, the mantle may have a bivalved form (Synagoga 

 and Petrarca), or it may form a capacious sac (Laura, Fig. 76) 

 much larger than the body, with which it is connected by a 

 narrow neck, and having only a small opening to the exterior. 

 In Demlrogaster (Fig. 78) the mantle is still more developed, and 

 is produced into branched lobes. In Laura the mantle is covered 

 with stellate papillae penetrating the tissues of the host, and pre- 

 sumably absorptive. In all cases the mantle contains ramifications 

 of the enteric diverticula and portions of the gonads. The body 



