XI 



PHYLUM ARTHUOPODA 



577 



permanently attached like the degenerate forms just described, but crawling 

 tivi'lv over the surface of the host. The body consists of an oval flattened 

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

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

 is a median tube ending in a spine (xt.). The second maxilla; are divided into 

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



Flo. 453. — Argulus foliaceus, young male, a*, untennulc ; « 2 > antenna; ab. abdomen ; 

 b\ — 64, thoracic feet ; d. digestive glands connected with intestine ; ifl, anterior or suctorial 

 feet ; kji, posterior or leg-like portion of second maxillst ; pa. paired eye ; /•. rostrum : ad. shell- 

 gland ; at. stylet ; It. testis ; tia, 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 (6/ —hlf). Alone among the Copepoda the Branchiura have no 

 egg-sacs, and they are exceptional also in the possession of compound eyes {pa. ). 



The most familiar examples of the Eucirripedia are the Barnacles 

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

 Barnacles, which occurin immense numbers on rocks between tide- 

 marks in all parts of the world. 



The common Barnacle {Lepas anati/era) is attached by a long 

 stalk or peduncle (Fig. 454, A,£>), covered with a wrinkled skin, and 

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



