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 

 cephalo-thorax, and a small bilobed abdomen (a&. ). The mandibles and maxilla- 

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

 is a median tube ending in a spine (st). The second maxilke are divided into 

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



FIG. 418. Argulus foliaceus, young male. j, antemmle ; 2 . antenna; ab. abdomen; 

 1>\ 64, thoracic feet ; <L digestive glands connected with intestine ; kfl, anterior or suctorial 

 feet ; kf2, 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 110 

 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 world. 



The common Barnacle (Lcpas anatifera) is attached by a long 

 stalk or peduncle (Fig. 419, fi^p)* coverecTwith a wrinkled skin, and 

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



