30 



2. Sicyonella antennata n. sp. PI. II, figs. 5« — 5^; PI. Ill, figs. \a — \f. 



Stat. 258. Dec. 12 — 16. Tual-anchorage, Kei-islands. 22 m. Lithothamnion, sand and coral. 



I male, i female. 

 The Copenhagen Museum possesses 14 specimens taken by Dr. Tn. MORTENSEN in 1900 in 



the Gulf of Siam at various localities, viz. between Koh Mesan and Cape Liant, 9 fathoms; 



Koh Kahdat, 4 — 5 and 5 fathoms, and South of Koh Mak, 5 — 6 fathoms. 



Description. — Rostrum with dorsal crest nearly as in Sic. maldivensis. Eyes distinctly 

 larger in the male (fig. i a) than in the female (fig. 1 <5) and larger than in the preceding species ; 

 in the female the distance from the base of the long second joint of the stalk to the end of 

 the cornea is distinctly more than twice as long as the breadth of the cornea, while in the 

 male the same distance is scarcely twice as long as that breadth. The antennular peduncles in 

 the female a little longer and distally more slender than in the female of Sic. maldivensis \ the 

 inner margin of the two distal joints combined is distinctly longer than that margin of first 

 joint; second joint a little longer than in Sic. maldivensis, with the inner margin slightly longer 

 than, or as long as, third joint. In the male the two distal peduncular joints are elongated, 

 the inner margin of both joints combined only somewhat less than twice as long as the inner 

 margin of first joint; third joint proportionately slender and considerably longer than the second. 

 The lower flagellum in the male (fig. 5«) in the main as in Sic. maldivensis. yet differing in 

 having a much lower number of spines on the concave margin. 



First pair of legs (fig. 5(^) a little more slender than in Sic. maldivensis; the chela is 

 shorter than fifth joint, a little more than six times as long as broad, and the hand is some- 

 what more than half as long again as the movable finger. Third pair of legs still more slender 

 than in Sic. maldivensis \ the chela of a female (fig. 5^) is about sixteen times as long as the 

 breadth of the hand at its middle, and the hand is somewhat more than three times as long 

 as the movable finger. 



The petasma (figs. \d — \f) differs strongly from that in Sic. maldivensis. The pars 

 externa is about as large as in Sic. maldivensis, but somewhat differently shaped ; the lamina 

 externa {latn.) is twice as long as broad, with the obtuse angle on the outer margin somewhat 

 before the middle ; processus uncifer {pn.) is considerably more than half as long as the lamina, 

 narrow from the base to the rounded end which has no incision. A processus basalis is not 

 developed. Processus ventralis [pv.) is very long, as in Sic. maldivensis divided into two branches, 

 but the proximal undivided part is more than one-third as long as the whole process; the 

 posterior branch is broad at the base, but tapers rapidly towards the middle, and distally it is 

 divided into two secondary branches (fig. i c), the inner nearly shorter than broad with a row 

 of small hooks along the terminal margin, while the other secondary branch is generally longer, 

 more narrow and directed much outwards, with some small hooks near the end ; the anterior 

 branch of processus ventralis is considerably shorter than the posterior, narrow excepting towards 

 the base which is extremely expanded, and the terminal part of the branch is somewhat widened 

 and rounded, with a good number of minute hooks on both sides. The capitulum, or distal 

 main portion of pars media excepting proc. ventralis, is so different from that in Sic. maldi- 

 vensis and from those in species of Sergestes known to me that I cannot interpret all the lobes 



