REPORT OY THE BRACHYURA. 
183 
Xiphonectes, A. Milne Edwards. 
Xiphonedes, A. Milne Edwards, Youv. Archiv. Mus. Hist. Yat., vol, ix. p. 157, 1873. 
This genus, established by A. Milne Edwards for certain small species which have 
much the appearance of Neptuni which have not attained their full development, is 
distinguished from Neptunus (subgenus Amphitrite ) by the following characters : — 
The carapace is narrower than is usual in Amjphitrite, the lateral epibranchial spine 
even more developed, and the lateral (or submedian) frontal lobes more prominent. The 
antero-lateral marginal teeth are spiniform, more remote from one another, and very 
rarely attain the number eight (exclusive of the lateral epibranchial spine) characteristic 
of Amphitrite. The orbits and eyes are very large. 
An examination of the series in the British (Natural History) Museum and Challenger 
collections, shows, I think, that the various described species of this genus must be 
regarded as varieties of one widely distributed type, which occurs throughout the Indo- 
Pacific region in water of only moderate depth (to 18 fathoms). 
Xiphonectes longispinosus (Dana). 
Amphitrite longispinosa, Dana, Proc. Acad. Yat. Sci. Philad. , p. 84, 1852; U.S. Explor. 
Exped., vol. xiii. Crust. 1, p. 277, pi. xvii. fig. 2, 1852. 
Amphitrite vigilans, Dana, tom. cit., p. 278, pi. xvii. fig. 3, var. 
Neptunus vigilans and longispinosus , A. Milne Edwards, Archiv. Mus. Hist. Yat., vol. x. pp. 336, 
337, 1861. 
1 Xiphonedes leptocheles, A. Milne Edwards, Youv. Archiv. Mus. Hist. Yat., vol. ix. p. 159, pi. iv. 
fig. 1, 1873, var. 
Neptunus vigilans, Richters, Decapoda in Mobius Beitr. zur. Meeresfauna der Mauritius und der 
Seychellen, p. 152, 1880. 
Xiphonedes vigilans, var. ohtusidentatus, Miers, Crust, in Rep. Zool. Coll. H.M.S. “Alert,” 
p. 538, pi. xlviii. fig. A, 1884. 
Tongatabu, 18 fathoms (Station 172), lat. 20° 58' 0 " S., long. 175° 9' 0" E. Two 
small males. 
These specimens offer a curious intermixture of the characters cited as characteristic 
of each of the supposed species, Xiphonectes longispinosus, Xiphonectes vigilans, and 
Xiphonectes leptocheles. In the larger specimen, the cheliped.es are comparatively robust 
as in the typical Xiphonectes longispinosus, in the smaller they are slender and elongated 
as in Xiphonectes leptocheles. In the larger specimen the arm or merus has four spines 
on its anterior (or inner) margin, as in the typical Xiphonectes vigilans, but the six spines 
of the antero-lateral margins are equidistant, as in Xiphonectes longispinosus. In the 
smaller specimen there are five spines on the anterior margin of the arm. In both speci- 
mens the post-abdomen is composed of only five distinct segments ; in the larger speci- 
men, with robust chelipedes, the sixth segment is more nearly of the form figured by 
