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Show 1899.] PARASITIC COPEPODA O N EISHES. 445 hooked claw, not extending beyond the carapace. Mouth as a more or less elongated suctorial beak, formed out of the upper and lower lip, in which is seen the slender mandible. Maxillipeds free, both in the form of hooks, the posterior being the most powerful; the first four pairs of thoracic limbs mostly biramose, but not infrequently the first and fourth uniramose, fifth pair rudimentary. Eye median, simple, frequently suppressed. Generative organs paired. External ovaries as two cord-like tubes. Male generally smaller than female; both sexes in the young of some genera attached by a slender frontal filament. DIVISION i. Caligince.-Terminal joints of most of the thoracic limbs fringed with plumose hairs. G. 1. HERMILIUS Heller. Carapace deeply notched in the centre, the two halves folding togetherlike the valves of a mussel. First and fourth pairs of thoracic limbs uniramose, second and third biramose. Fourth thoracic segment small, free, not provided with dorsal plates. (1) HERMILIUS PYRIVENTRIS. 2 • Hermilius pyriventris Heller, Beise d. Novara, 1865, p. 186, pl. xviii. fig. 1. Host: gills of Arius acutus [A. argyropleuron]. Java. (2) HERMILIUS LONGICORNIS. 2 • Hermilius longicornis B.-S. Ann. & Mag. N. H. ser. 7, vol. ii. 1898, p. 30, pl. iii. fig. 2. In Coll. Brit. Mus. Host: Arius acutirostris. Trincomalee. G. 2. PARAPETALUS Stp. & Liitk. Carapace rouuded, scutiform. Frontal border with lunulae. First and fourth pairs of thoracic limbs uniramose, second and third biramose. Genital segment of large size, covered over by two dorsal plates; also with two elongated flattened processes projecting backwards from the posterior border and origin of abdominal portion ; which latter is particulate, terminating in two small caudal plates. (1) PARAPETALUS ORIENTALIS. $ . Parapetalus orientalis Stp. & Liitk. Bidrag til Kundskab, 1861 p. 365, pl. v. fig. 10. Host: gills of Mene maculata. Indian Ocean. G. 3. SYNESTIUS Stp. & Liitk. Carapace rounded, scutiform. Frontal border with lunulae. First and fourth thoracic limbs uniramose ; second and third biramose. Genital segment large, not covered by dorsal plates, but prolonged |
