THE CIRRIPEDIA 



129 



proceed two ribbon-like filaments (Fig. 79, A, ant), bearing at the 

 tip the larval antennules, which agree in structure, as already 

 noticed, with the type usual among normal Cirripedes. The six 

 following "segments" were regarded by Darwin as thoracic and 

 the three remaining as abdominal. All of them are devoid of 

 any trace of appendages. 



The alimentary canal is greatly reduced. According to Darwin, 

 only the oesophagus is present, and there is no trace of stomach, 

 rectum, or anus. The ovaries lie at the sides of the anterior part 

 of the body and the testes posteriorly. The vasa deferentia unite 

 to open at the tip of the abdomen. There is no penis. 



B. 



FIG. 70. 



biviiicttt. A, the entire animal ; ant, antennules ; B, buccal cone : gl.ce, cement- 

 gland ; p.p, penial papilla ; test, testis ; v.s, .seminal vesicle. B, diagrammatic pla:i of month- 

 parts ; l.s, upper lip; tad, mandibje ; wix, maxillula; mx 1 , maxilla. C, mandible and maxillula 

 separated ; in, muscle. (After Darwin, from Gruvel's Monographic.) 



While Darwin was unable to investigate the development of 

 the species, Hansen has recently conjecturally referred to the 

 Apoda certain nauplius larvae obtained in various parts of the 

 Atlantic Ocean and the Baltic, while more recently similar larvae 

 have been found in the Adriatic Sea. In late nauplius stages of 

 this type rudiments of paired compound eyes and of six pairs of 

 thoracic limbs are visible, so that it can hardly be doubted that 

 they belong to some form of Cirripede. On the other hand, they 

 differ markedly in the absence of antero-lateral horns and of frontal 

 filaments, in the shape of the body, and especially of the strongly 

 developed dorsal shield, and in other characters from the known 

 Cirripede larvae, which, as already indicated, show great uniformity 



