62 Bulletin Vanderbilt Marine Museum, Vol. VI 



tubercles of varying number. 



There are four pairs of pleopoda, these successively decreas- 

 ing in size in the order 1, 2, 3, 4 ; the first pair, when flexed in- 

 ward, having its larger blade reaching scarcely two-thirds of 

 the distance to the median line. Each pleopod consists of a small, 

 stout peduncle, a large, ovate, outer blade and a distinctly smaller 

 inner blade, which is scarcely two-thirds as long and less than half 

 as wide, more lanceolate than ovate distally. 



The external maxillipeds are as figured (Plate 15, fig. B). 

 The five pairs of legs are monodactylar, fragile, successively 

 decreasing in the order 1 to 5. The dactyli of pairs 1, 2 and 3 are 

 similar, very curved and pointed, claw-like, while the dactyli of 

 pairs 4 and 5 are shorter and so appear less hooked, but each in 

 reality has a stout horny nail-tip. 



References : Ursu^ cancer, Rumphius, G., D'Amboinsche Rari- 

 teitkamer, vol. I, 1705, p. 3, pi. 2, fig. D. 



Cancer arctus, LiNNE (part) , Syst. Nat., ed. X, 1758, p. 633. 

 Scyllarus arctus (part), Fabricius, Syst. Entom., 1775, p. 413; 

 Ent. Syst, vol. II, 1793, p. 47. 



Cancer {Astacus) arctus, Herbst (not C. arctus Linne, s. s.), 

 Naturg. Krabben u. Krebse, Bd. II, pt. 3, 1793, p. 80, pi. 30, 

 fig. 1. 



Scyllarus orientalis, LUND, N. T., Skrivter Nat. Hist. Selsk., vol. II, 

 pt. 2, 1793, p. 22.— Fabricius, Suppl. Ent. Syst., 1798, p. 

 399. — Latreille, Hist. Nat. Crust, et Insectes, t. VI, 1803, p. 

 181. — Desmarest, Consid. Gen. Crust., 1825, p. 182, pi. 31, 

 fig. 1. 



Thenus indicus, Leach, Trans. Linn. Soc. London, Zool., vol. XI, 

 1815, p. 338; Encycl. Brit., ed. V, 1816, suppl., p. 419. 



Thenus orientalis, Edwards, H. Milne, Hist. Nat. Crust., t. II, 

 1837, p. 286; Regne Anim., illustrated edition, undated, pi. 

 45, figs. 2a-c. — Hoffman, in Pollen and Van Dam's Recher- 

 ches Faune de Madagascar et Dependances, vol. 1, 1874, pt. 5, 

 Livr. 2, p. 42. — MiERS, E. J., Ann. and Mag. Nat. Hist., ser. 5, 

 vol. V, 1880, p. 378. — de Man, J. G., Archiv. f. Naturges. 

 Gesel., vol. LIII, pt. 1, 1887, p. 486 ; Journ. Linn. Soc. London, 

 vol. XXII, 1888, p. 201.— Bate, C. S., Rept. Voy. H. M. S. 

 "Challenger," Zool, vol. XXIV, Macrura, 1888, p. 66.— Hen- 

 derson, J. R., Trans. Linn. Soc. London, Zool., ser. 2, vol. 



