44 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 53. 



row into the tissues of the host by means of the antennae and the 

 mouth parts and finally reach the intestines, where they are per- 

 manently anchored by the outgrowth of processes or horns from the 

 sides of the cephalothorax. 



Genus PENICULUS Nordmann, 



Pcnicxilus NoEDMANN, Mikrographische Beitriige, 1S32, p. 107, pi. 6, figs. 

 8 to 14. 



External generic characters of female. — Cephalothorax distinctly 

 separated from the rest of the body, elliptical, flattened dorso-ven- 

 trally, covered with a carapace which often shows lateral lobes, and 

 destitute of horns or processes; neck composed of second and third 

 thorax segments, much narrowed, flattened dorso-ventrally, and 

 chitinized; fourth segment more or less spherical and much widened; 

 trunk composed of the fifth and genital segments fused and a 

 minute abdomen; Qgg strings slender and much longer than the 

 trunk; eggs uniscriate. Second antennae strongly chelate; eye tri- 

 partite and deeply buried; probosis long, conical, and retractile; two 

 pairs of maxillae; second pair uncinate. 



Internal generic characters of female. — Esophagus strongly in- 

 clined to the body axis; stomach only slightly enlarged and without 

 convolutions; intestine straight, much wider than the stomach, 

 dorsal and abruptly contracted into a very short rectum (fig. 14) ; 

 well-defined supra and infra esophageal ganglia with distinguish- 

 able nerves; ovaries dorsal to the intestine and near the anterior end 

 of the trunk; oviducts passing from the anterior ends of the ovaries 

 around the intestine to the ventral surface and straight back to the 

 vulvae; oviducts long and comparatively narrow; cement glands 

 close together and A'entral to the oviducts, the glandular portion as 

 wide as, or wider than, the oviducts and usually distinctly seg- 

 mented, the ducts sometimes parallel, sometimes convergent pos- 

 teriorly and opening into the oviducts near the vulvae; paired 

 digestive glands on either side of the esophagus and anterior stom- 

 ach; paired excretory glands on the ventral surface of the fourth 

 thorax segment. 



Genus habitat. — This genus does not burrow into the tissues of its 

 host, but is always found upon the fins, usually the dorsal fins. It 

 fastens itself to the bone of one of the fin rays by means of its second 

 antennae, and the chelae of these antennae are usually so covered 

 with osseus tissues whose growth is induced by the irritation, that 

 it is impossible to separate them from the ray. 



Type of the genus. — Peniculus fistula Nordmann, monotypic. 



(Peniculus, the name of a parasite in Plautus.) 



Remarks. — This genus was established and meagerly described by 

 Nordmann but was not definitely located. Milne Edwards placed it 



