The Isopods of Abyssal Depths in the Atlantic Ocean

110 ROBERT J. MENZIES
Figure 15. A-H: Hydroniscus ornatus, n. sp. A: dorsal view female allotype; B: maxilliped;
C: dorsal view uropod; D: first peraeopod; E. mandible; F: second antenna; G: first
antenna; H: first pleopod. I-M: Hydroniscus quadrifrons, n. sp. I: dorsal view male holotype;
J: first antenna; K: second pleopod; L: first pleopod; M: uropod. N-O: Hydroniscus
abyssi Hansen (after Hansen, 1916). N: dorsal view female; O: pleon and anus.
present. Flagellum of first antenna with five articles.
Dorsum of cephalon tuberculate, rostrum blunt at apex.
Measurements: Male holotype length 2.7 mm., width
pleon 1.0 mm., allotype length 3.2 mm., width pleon
1.1 mm., and four male and six female paratypes.
Type locality: North Atlantic, L.G.O. Biotrawl
No. 231, types, cat. no. 1-51.
Distribution: Also known from L.G.O. Biotrawl
No. 214, one female, cat. no. 1-53; L.G.O. Biotrawl
No. 229, one male and one fragment, cat. no. 1-58;
L.G.O. Biotrawl No. 232, one fragment, cat. no.
1-55; L.G.O. Biotrawl No. 233, one male, one frag­
ment, cat. no. 1-56; L.G.O. Biotrawl No. 234, three
males, cat. no. 1-57.
Affinities: This species is related to H. abyssi
Hansen, from which it differs in having a blunt
rostrum and in having uropods, and to ornatus, from
which it differs in having a blunt rostrum.
Hydroniscus abyssi Hansen
Figure 15 N-O
Synonyms: Hydroniscus abyssi Hansen, 1916, p. 33,
PI. II.