532 



ZOOLOGY 



SECT- 



permanently attached like the degenerate forms just described, but crawling 

 freely over the surface of the host. The body consists of an oval flattened 

 ceplmlo-thorax, and a small bilobed abdomen (ab.). The mandibles and maxilla? 

 are piercim- organs enclosed in a sucking-tube or proboscis (r.), in front of which 

 is a median tube ending in a spine (sf). The second maxillae arc divided into 

 two portions the anterior of which (//. 1) are modified into sucking-discs, by 



Fii:. 418. Argulus foliaceus, young male, n\, aiiteniiulc ; 11-2, antenna; all. abdomen r 

 //] /, 4 , thoracic feet ; <l. digestive glands connected with intestine; kfl, anterior or suctorial 

 feet ; /('.', posterior or leg-like portion of second maxilla; ; pa. paired eye ; r. rostrum ; sd, shell - 

 gland; st. stylet; ts. testis ; ua, median eye. (From Lang's Comparative Anatomy.) 



which the parasite clings to the surface of its host, and there are four pairs of 

 swimming-feet (bl b4). Alone among the Copepoda the Branchiura have no 

 egg-sacs. 



The most familiar examples of the Eucirripedia are the Barnacles 

 found on ships' bottoms, piles, &c., and the Acorn-shells or Sessile 

 Barnacles which occur in immense numbers on rocks between tide- 

 marks in all parts of the w< nid. 



The common Barnacle (Zr^/s anatifera) is attached by a long 

 stalk or peduncle (Fig. 419, A, p}, covered with a wrinkled skin, and 

 at its distal end the body proper enclosed in a sort of 



