No. 2194. NOliTH AMEJilVAN PAltAtSlTW VOPEl^ODiS— WILSON. 83 



the female for a permanent host. To this fish's gills it adheres by 

 menus of the chelate second antennae and proceeds to fasten itself 

 to the apex of the gill filament by a broad frontal band of chitin. 

 While thus attached it passes through two or three pupal stages dur- 

 ing which there is the same disappearance of segmentation and of 

 setae in the appendages as occurs in the Lernaeenicinae (see p. 43). 

 But the reproductive organs develop, the body of the female elon- 

 gates considerably, both sexes reach maturity, and fertilization takes 

 place. The female, and sometimes also the male, then sever their 

 connection with the gill filament and swim about again freely in 

 the plankton. 



The male soon dies, but the body of the female elongates still more 

 and she then seelcs out a final host and fastens to its gill arches with 

 her chelate second antennae. She finally burrows flirough the inter- 

 vening tissues to the immediate vicinity of the heart or the ventral 

 aorta, where the head is securely anchored by the outgrowth of 

 branched chitin Horns. Here the female remains as a fixed parasite 

 during the-remainder of her life, which probably lasts a year or more. 



Genus LERNAEOCERA Blainville. 



Lcrnaca (part) Linnaeus, Systema Naturae, ed. 12, 1767, vol. 1, pt. 2, p. 1092. 

 Lerncoccra Blainville, Joiirn. de Physique, vol. 95, 1822, p. 375. 

 Lcrncoccra (part) Noedmann, Jlikrograpliische Beitrjige, 1S32, p. 130. 

 Lernaea Burmeister, Acta Acad. Caes. Leop. Nat. Cur., vol. 17, 1S33, p. 319. 

 Lernaca (part) Milne Edwards. Ilistoire Naturelle des CrustacSs, vol. 3, 



1S40, p. 528. 

 Lernaca, all subsequent authors. 



External generic characters of female. — Ceplialothorax globular, 

 comparatively small, and furnished with three branched chitinous 

 horns or anchor processes, the dorsal one usually a little longer than 

 the lateral ones; second, third, and fourth thorax segments in the 

 form of a slender neck of moderate length and of about the same 

 diameter throughout; fifth and genital segments fused and more or 

 less swollen, and with tlie abdomen bent into the form of the letter 

 S; abdomen distinctly separated from the genital segment in im- 

 mature stages, but completely fused in the mature adult; egg strings 

 filiform, many times the length of the body, and coiled into irregular 

 masses. First antennae three-jointed and well supplied with setae; 

 second pair chelate and two-jointed; two pairs of maxillae, but no 

 maxillipeds; first two pairs of swimming legs biramose, two posterior 

 pairs uniramose, all the rami two-jointed. 



Internal generic characters of female. — ISIouth really terminal, but 

 appearing lateral, owing to the inclination of the head; esophagus 

 nearly in line with head axis; stomach without lateral processes or 



