352 



CRUSTACEA 



ARGTILUS 0. F. Miiller. Suckers and sting present: 27 species, 

 parasites on marine and fresh-water fish, usually in the branchial cavity; 

 13 American species. 



A. laticauda S. I. Smith. Carapace elliptical, considerably longer 

 than wide and not reaching the abdomen, which is broadly elliptical; 

 length 6 mm. : on the eel, flounder, and other marine fishes ; common. 



A. catostomi Dana & Herrick. Carapace round, wider than long, 

 and reaching the abdomen, which is round and wider than long; length 

 12 mm.; color light green: on fresh-water fish, especially the sucker 

 (New England). 



A. funduli Kroyer. Carapace wider than long and not reaching the 

 abdomen, which is very long, being 3 times as long as wide; length 5 

 mm. : on Fundulus along the Atlantic coast. 



A. versicolor C. B. Wilson (Fig. 555). Length 6 mm.; width 4.9 

 mm.; color brilliantly variegated: in gill cavity of pickerel. 



ORDER 3. OSTRACODA.* 



Body without segmentation and laterally compressed, and entirely 

 enclosed in a bivalved carapace. The two sides of the carapace can 



be closed by a retractor muscle; when 

 they open, the appendages are thrust out 

 and propel the animal through the water. 

 Seven pairs of appendages are present 

 (Fig. 556, B). The two pairs of antennae 

 are used for both locomotion and orienta- 

 tion, the second pair being either biramose 

 or uniramose. The mandibles have each a 

 large 3 or 4-jointed palp; two pairs of 

 maxillae are present, of which the second 

 pair are usually leg-like. Two pairs of 

 legs follow, the second pair sometimes 

 being bent back and apparently of use 



only in keeping dirt out of the shell. The abdomen is short and may end 

 in a projection with two terminal claws called the furca. The internal 



* "A Monograph of the Marine and Freshwater Ostracoda," by G. S. Brady, and 

 A. M. Norman, Trans. Royal Dublin Soc. Vols. 4 and 5, 1889 and 1896. "Synopsis of 

 Freshwater Ostracoda," by C. H. Turner, Am. Nat., Vol. 33, p. 877, 1899. "Rep. on 

 the Freshwater Ostracoda of the TJ. S.," etc., by R. W. Sharpe, Proc. U. S. Nat. Mus., 

 Vol. 26, p. 969, 1903. "Marine Ostracoda of Vineyard Sound and Adjacent Waters," 

 by J. A. Cushman, Proc. Bost. Soc. Nat. Hist., Vol. 32, p. 359, 1906. "The Ostracoda 

 of the San Diego Region, II, Littoral Forms," by C. Juday, Univ. Cal. Pub., Vol. 3, p. 

 135, 1907. "Die Siisswasserfauna Deutschlands," Heft 11, 1911. "Ostracoda," by 

 G. W. Miiller, Das Tierreich, 1912. 



Fig. 555 Arfjulus versicolor 

 (Wilson). 



