624 
CLASS X. 
I think it is only a monstrous variety of Limulus moluccanus. Several 
fossil species are known from the lithographic formation ; see my monograph, 
Tab. 7. 
OrveER II. ILchthyophthira. 
Mouth suctorial. Rostrum tubular, including two mandibles 
setaceous, acuminate, formed of labium and labrum conjoined, 
sometimes concealed, or a tubercle instead of haustellum. Anterior 
feet supplied with hooks or acetabula for fixing the body. Animal- 
cules, in the adult state, adhering parasitically to fishes, often 
deformed, soft, with segments obsolete. Females supplied with 
oviferous appendages (external ovaries). 
Fish-lice. We prefer this name to that of Parasita, introduced 
by WIEGMANN, because in the class of insects an order of Parasitica 
had been previously adopted. The animals when young swim 
freely about, by means of feet with long hairs, and resemble the 
young animals of Cyclops. 
Comp. on this order BLAINVILLE Mémoire sur les Lernées, Jowrnal de 
Physique, de Chim., @ Hist. nat. &c. Tom. 95, Paris, 1822, pp. 372—380, 
and pp. 437—447, and by the same the Article Lernée in Dictionnaire des 
Sciences nat. XXVI. 1823, pp. 112—130. A. Von NorpMann WMikrogra- 
phische Beitrdge, 2tes Heft. Berlin, 1832, 4t0. H. BurMEIsTER Beschret- 
bung einiger Schmarotzerkrebse. Nov. Act. Acad. Ces. Leop. XVII. 1835, pp. 
269—336; H. KroryverR Om Snyltekrebsene, Naturh. Tidsskr. 1. 1837, pp. 
172 and foll., pp. 252 and foll., pp. 470 and foll., pp. 605—628, 11. 1838, 
pp: 8—52, pp. 131—157. 
Family Il. Lerneacea (Penellina Burm.) Body in adults not 
articulate, cylindrical or sacciform. Articulate feet none. 
Lernea Li. (Lerneocera Buatnv., V. Norpm.). Body ventri- 
cose, mostly incurved. Three or four appendages, branched at the 
apex or bifid, around the head, for fixing the body. 
Sp. Lerneea branchialis L., Encyl. méth., Vers. Pl. 78, fig. 2, GuERIN Iconogr., 
Zooph. Pl. 9, fig. 1; with three branched little horns on the head; the 
ovisacs are two long tortuous strings; this species fixes itself to the gills of 
the cod-fish; comp. C. N. (OzEmaAn) Vitgezogte Verhandelingin, 11. 1757, 
bl. 282 and foll., Pl. 14, 11. bl. 232 and foll., Pl. 23. 
There was much doubt formerly respecting the place of these gill-worms 
in the natural arrangement of the animal kingdom. CuviER placed them 
amongst the intestinal worms (intestinaua cavitaires, see R. Ant. 2e Edit. 
III. p. 255), as a distinct and anomalous family. The resemblance to some 
other parasites, which had been referred to the crustacea, caused indeed a 
