74 Bulletin Vanderbilt Marine Museum, Vol. VI 



The antennae support a large scaphocerite, which is a little 

 longer than the antennular peduncle and has a distinct outer 

 lateral carina terminating in a very acute, subdistal tooth and a 

 strong groove parallel and adjacent to this carina; the flagellum 

 is two and a third times as long as the body. 



The first, second and third pairs of legs are chelate ; each has 

 an antrorse spine on the basis. 



In the adult males, the fifth pair of legs are specialized, as de- 

 scribed and figured by Dr. Alcock. The fifth pair of legs of both 

 sexes are slender ; the dactyli extending to about two-thirds of the 

 length of the scaphocerite. 



The petasma is figured by Dr. Alcock. 



The thelycum is concave, the concavity being limited laterally 

 by a pair of auricular lobes, the free, anterior margin of which is 

 usually incurved, and anteriorly there projects a narrow, tongue- 

 like process, with rounded distal margin. This process lies be- 

 tween the two rounded pad-like lobes, each of which is attached 

 to the inner angle of the basis of the fourth leg. 



References: Peneus monoceros, Fabricius, J. C, Entom. Syst. 

 Suppl., 1798, p. 409.— Edwards, H. M., Hist. Nat. Crust., t. 

 II, 1837, p. 415.— Dana, J. D., Rept. U. S. Explor. Exped. 

 Crust., vol. XIII, 1852, p. 605; Atlas, 1855, pi. 40, fig. 5.— 

 Stimpson, W., Proc. Phila. Acad. Sci., vol. XII, 1860, p. 44 

 (part) . — MiERS, E, J., Proc. Zool. Soc. London, 1878, p. 301. — 

 Hilgendorf, F., Monatsb. k. Preuss. Akad. Berlin, 1878, 

 p. 844. — Bate, C. S., Ann. Mag. Nat. Hist., ser. 5, vol. 

 VIII, 1881, p. 177, pi. 11, fig. 2.— Haswell, W. A., Cat. 

 Austral. Stalk and Sessile-eyed Crust., 18882, p. 200. — Ort- 

 MANN, A., Zool. Jahrb. Syst., Bd. V, 1890, p. 450 (part), 

 pi. 36, fig. 3b but not 3a. — Thallwitz, J., Abh. u. Berlin Mus. 

 Dresden, No. 3, 1890-91, p. 2.— DE Man, J. G., in Weber's 

 Zool. Ergebn. Niederl. Ost.-Ind., Bd. II, 1892, p. 513, pi. 

 54; also in Zool. Jahrb. Syst., Bd. X, 1898, p. 680.— Doflein, 

 F., Munchen, Ak. Wiss. Abh. Math.-Physik. CI., Bd. XXI, 

 1900-02, p. 631. 



Metapenaev£ monoceros, Nobili, G., Boll. Mus. Torino, t. XVIII, 

 1903, no. 452, p. 3; also no. 455, p. 3. — Alcock, A., Catal. 

 Indian Decap. Crust. Coll. Indian Mus., pt. Ill, Macrura, fasc. 

 I, Peneus group, 1906, p. 18, pi. 3, fig. 7, 7a-c. 



