27G 



ZOOLOGY. 



concealing the rudimentary antennae, and the feet grow 

 smaller, and eventually the barnacle-shape is attained. The 



Fig. -M. Pupa of Lepas, much eu- 

 hirged. After Durwm. 



Fig. 227.Nauplius of Balanus bat- 

 anoides, much enlarged. 



common barnacle (Balanus balanoides) attains its full size, 

 after becoming fixed, in one season, i. e., between the first of 

 April and November. 



Still lower than the genu- 

 ine barnacles are the root-bar- 

 nacles or Rliizocepliala, repre- 

 sented by Peltogaster (Fig. 

 229) and Saccnlina (Fig. 230), 

 in which the young is a more 

 simple Nauplius form, like 

 the young of the Entomostra- 

 ca, while the adult is a sim- 

 ple sac, with a ganglion, but 

 no digestive organs. From 

 the feet of the young grow 

 out, after the animal becomes 

 sessile, long root - like fila- 

 ments, which ramify in the 

 body of the crab, to which 

 these animals are firmly an- 



Fig. 229. Peltogaster curvatn*, en- 



We Can Conceive Ot largedlj times, beneath the larva or N;m- 



plius of Parthenopea, enlarged al>out ^op 

 times. From Brehm's Thierleben. 



, , 

 no lower, more degraded 



tacean than these root-barna- 

 cles, the only signs of life being the powerful contractions 

 of the roots and an alternate expansion and contraction of 



