ART. 5. 2?0RTH AMERICAN PARASITIC COPEPODS WILSON. 53 



Genus PENICULISA Wilson. 



PenicuUsa Wilson, Proc. U. S. Nat. Mus., vol. 53, 1917, p. 45. 

 Peniculus (part) Kr0yer, Naturhistorisk Tidsskrift, ser, 3, vol. 2, 1863, 

 p. 268. 



External generic characters of female. — First thorax segment more 

 or less distinctly separated from the head and with the second and 

 third segments forming a sort of neck which is narrowed but not 

 chitinized. Head elliptical, flattened, and covered with a dorsal 

 carapace. Fourth, fifth, and genital segments fused, flattened, and 

 covered with a dorsal plate. Posteriorly this fused trunk is pro- 

 longed into a wide flattened process on either side of the abdomen. 

 The latter is small, one-jointed, and also prolonged into a flattened 

 process at each posterior corner. Egg strings short and stout; eggs 

 uniseriate and well flattened. 



First antennae reduced to mere knobs ; second pair much enlarged, 

 uncinate, and prehensile ; no maxillae ; maxillipeds large, with strong 

 claws. 



Three pairs of rudimentary uniramose legs on the first three thorax 

 segments ; a fourth pair on the fused trunk some distance behind the 

 anterior end. 



Internal generic characters of female. — Esophagus inclined for- 

 ward and entering the ventral surface of the stomach near the 

 anterior end. Stomach narrowed into an intestine in the free thorax 

 segments; intestine widened in the fused trunk and contracted into 

 a short rectum in the abdomen. Ovaries dorsal to the intestine in 

 the extreme anterior part of the fused trunk, oviducts much convo- 

 luted and occupying all the space dorsal and lateral to the intestine. 

 Cement glands close together in the posterior portion of the fused 

 trunk and ventral to the oviducts, the glandular portion an elongated 

 ellipse, only reaching forward to the center of the trunk, the ducts 

 very short. Semen receptacle on the floor of the trunk at the pos- 

 terior end. 



External generic characters of male. — General form similar to that 

 of the female, but with differences in the body proportions. Pos- 

 terior processes on the genital segment only a third as long as in the 

 female, spatulate, strongly flattened at the tips. Abdomen without 

 posterior processes, almost hemispherical in shape; anal laminae 

 relatively larger and their setae longer. Antennae, mouth parts, and 

 appendages similar to those of the female, except that the maxillipeds 

 are larger and much stouter. 



Type of the genus. — PenicuUsa furcata (Kr0yer), monotypic. 



Remarks. — In these Proceedings (vol. 53, 1917, p. 45) certain rea- 

 sons were presented for excluding the species furcatus from the genus 

 Penicidiis, where Kr0yer had placed it, and establishing it as the 



