596 ORDER APODA. 



inclosing the cement-ducts, which spring from the second 

 segment of the body (or first of the thorax), and which termi- 

 nate within the prehensile antennae of the pupa, we shall 

 hereafter see that their apparently most anomalous position, 

 and even the flattened shape of the dorsal surface of the 

 two anterior segments of the body, all accord perfectly with 

 the homologies just given. 



Alimentary Canal. — The oesophagus is thin, and for a 

 cirripede short, for it extends only half-way down the first 

 segment (t. e. last cephalic) of the body ; the lower end, 

 which is slightly dilated, nearly touches the anterior end of 

 the great ovarian sack. At its upper end, it is surrounded 

 by delicate, striae-less constrictor muscles ; and there are 

 others radiating outwards, evidently serving to open it : 

 the lower part of the oesophagus, differently from other 

 cirripedes, is destitute of muscles, and is only coated by a 

 thin layer of corium, which would serve to produce a new 

 oesophagus at each exuviation. Strange as the fact may be, 

 I am prepared to assert that there is no stomach, rectum, 

 or anus. As 1 was able to trace so distinctly the oesophagus, 

 and likewise the generally far smaller orifice and ducts of 

 the male generative organs, I consider it quite impossible 

 that I could have missed the stomach. The rectum and 

 anus are absent in Alcippe : and the absence of a stomach 

 is here in some degree the less surprising, as the structure 

 of the mouth shows that Proteolepas must live on the already 

 elaborated fluids of the Alepas, to which, being a cirripede, 

 it is allied. It is of some importance to observe, that the 

 oesophagus is fitted with muscles simply for shutting and 

 opening it, the wave-like swallowing action of which other 

 cirripedes are capable, being, apparently, here impossible ; 

 but the contraction of the body and its subsequent ex- 

 pansion, the oesophagus being opened, would allow the blood 

 of its prey to flow inwards. 



The nervous system must be much atrophied, for I could 

 not detect it, and the small size of the animal is not sufficient 

 to account for this : I wish I could have seen this system, 

 for then I should almost certainly have beheld an articulate 

 animal without a trace of a supra-cesophageal ganglion. 

 There is no eye, but such could hardly be expected, as the 



