AKT. 5. NORTH AMERICAN PARASITIC COPEPODS WILSON. 19 



ONTOGENY. 



Nothing is known of the development of any genus beyond the 

 nauplius stage. Such nauplii as have been obtained will be described 

 under the various species to which they belong. 



SYSTEMATIC DESCRIPTIONS. 



Family DICHELESTHIIDAE. 



Anthosomadae Baird, British Entomostraca, 1850, p. 296. 



Caligidae, Race I Leach, Dictionaire des Sciences Naturelles, vol. 14, 1819. 



p. 524. 

 Caligidae, Race I Desmaekst, Des Crustac6s, 1825, p. 334. 

 Ergasilina, Division B BtiBMEiSTEai, Acta Acad. Caes. Leop. Carol. Nat. 



Cur., vol. 17, 1833, p. 328. 

 Ergasilina, Division B Kr0yer, Naturbistorisk Tidsskrift, vol. 1, 1837, 



p. 198. 

 Dichelestidae Milne Edwards, Histoire Naturelle des Crustac6s, 1840, 



p. 481. 

 Lernaeifomiidae Nordmann, Mikrographische Beitrage, pt. 2, 1832, p. 55. 

 Dichelestini Nordmann, Bulletin Soc. Imp. des Nat., Moscou, vol. 37, 1864, 



p. 474. 

 Dichelestina Heller, Reise der Novara, 1865, p. 212. 

 Dichelesthiina Gerstaecker, Bronn's Klassen und Ordnungen, vol. 5, 1871, 



p. 724. 

 DicJielesthiidae M. J. Rathbun, Fauna of New England, 1905, p. 97. 

 Dichelesthiidae Brlin, Copepodi Parassiti del Pesci d'ltalia, 1906, p. 62. 

 Dichelestiidae Calman, Lankester's Zoology, pt. 7, fas. 3, 1909, p. 103. 

 Dichelestiidae T. and A. Scott, British Copepoda, 1912, p. 105. 



Family characters of female. — General body form long and nar- 

 row ; head fused with first thorax segment and the two covered with 

 a carapace ; free thorax segments usually simple, but sometimes fur- 

 nished with wings or dorsal plates or both; abdomen small and un- 

 segmented; egg strings long and filose; eggs uniseriate, sometimes 

 strongly flattened, sometimes swollen into separate spheres. 



Two pairs of antennae, first pair slender and setose, second pair 

 stout and uncinate; mouth parts similar to those of the Caligidae; 

 one pair of mandibles, two pairs of maxillae, one pair of maxilli- 

 peds; usually four pairs of swimming legs, third and fourth pairs 

 sometimes transformed into lamelliform plates, or rudimentary, or 

 even lacking. 



Family characters of male. — Smaller than the female, but not a 

 pygmy; head and first thorax segment fused and covered with a 

 carapace; remaining thorax segments fused and sometimes covered 

 with a dorsal plate, but never furnished with wings; abdomen mi- 

 nute and unsegmented. 



Antennae and mouth parts similar to those of the female ; swim- 

 ming legs also similar, with sometimes a fifth pair on the genital 

 segment. 



