1899.] PAEASITIO COPEPODA ON MSHES. 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 maadible. Maxilhpeds free, 

 both in the form of hooks, the posterior being the most powerful ; 

 the first four pairs of thoracic limbs mostly biramose, but not in- 

 frequently the first and fourth uniramose, fifth pair rudimentary. 

 Eye median, simple, frequently suppressed, (xenerative 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. Oaligince. — Terminal joints of most of the thoracic 

 • limbs fringed with plumose hairs. 



Gr. 1. Hermilius Heller. 



Carapace deeply notched in the centre, the two halves folding 

 together like theA'alvesof 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) Heemilius pyeiventbis. § . 



Hermilius ijyriventris Heller, Eeise d. Novara, 1865, p. 186, 

 pi. xviii. fig. 1. 



Host : gills of Arius acutus [A. argyropleuron]. Java. 



(2) Heemilius longicoenis. 2 . 



Hermilius lonqicornis B.-S. Ann. & Mag. N. H. ser. 7, vol. ii. 

 1898, p. 30, pi. m. fig. 2. 

 In Coll. Brit. Mus. 

 Host : Arius acutirostris. Trincomalee. 



G. 2. Paeapetalus Stp. & Liitk. 



Carapace rounded, scutiform. Frontal border with lunulas. First 

 and fourth pairs of thoracic limbs uniramose, second and third bira- 

 mose. Genital segment of large size, covered over by two dorsal 

 plates ; also with two elongated flattened processes projecting back- 

 wards from the posterior border and origin of abdominal portion ; 

 which latter is biarticulate, terminating in two small caudal 

 plates. 



(1) Paeapetalus oeibntalis. 5 . 



Parapetalus orientalis Stp. & Liitk. Bidrag til Kundskab, 1861, 

 p. 365, pi. V. fig. 10. 



Host : gills of Mene maculata. Indian Ocean. 



Gr. 3. Synestius Stp. & Liitk. 



Carapace rounded, scutiform. Frontal border with limulae. First 

 and fourth thoracic limbs uniramose ; second and third biramose. 

 Genital seguient large, not covered by dorsal plates, but prolonged 



