's RIJKS MUSEUM VAN NATUURLIJKE HISTORIE — LEIDEN. 85 



of the shore immediately below that in which the Talitri are commonly 

 found" (Stebbing, p. 328). 



2. Orchestia bottae H. Milne-Edwards. 



This species, insufficiently characterized by H. Milne-Edwards (Hist, 

 nat. d. Crustacés, t. Ill, 1840, p. 17) has been made better known, under 

 the same name, by Brandt (Bull, physico-mathém. de l'Àcad. de St. Pé- 

 tersbourg, t. IX, 1851, p. 142), by Czerniavsky (Mater, ad zoographiam 

 ponticam comparatam, 1868, p. 117, pi. VIII f. 28 — 32) and above all 

 by Chevreux (Rev. biol. d. nord d. 1. France, t. VII, 1895, p. 156 f. 1—4). 

 Heller described it as a new species under the name of 0. cavimana 

 (Verh. zool.-bot. Gesellsch. Wien, Bd. 15, 1865, p. 979, pi. 17) and this 

 designation has been used by Hoek (Tijdsch. Ned. Dierk. Ver. ser. 1, 

 D. IV, 1879, p. 131 pi. IX f. 8—10) and by Xebeski (Arb. zool. Inst. 

 Wien, Bd. Ill, 1881, p. 142, pi. 2 f. 10). Neither of these authors seems 

 to have been aware of the synonymy of 0. bottae and 0. cavimana] as 

 far as I know it has been Stebbing for the first time („Tierreich", 

 Amphipoda, Lief. 21, 1906, p. 534) who united the two names. Delia 

 Valle (Fauna u. Flora d. Golfes v. Neapel, Gammarini, 1893, p. 500) 

 ranges both names under O. gammarellus (Pallas). 



The figures that best characterize the species under discussion are 

 those of Hoek and Chevreux; that of Nebeski, though reprinted in some 

 text-books (R. Hertwig, Lehrbuch d. Zoologie, ed. 4, 1897, p. 386 f. 382 

 and Bronn's Klassen u. Ordn., Crustacea, Abt. II, pi. XXXIX) not being 

 quite accurate in representing the gnathopods and the second joint of 

 the three last pairs of pereiopods. 



0. bottae very much resembles the common 0. gammarellus, but, ex- 

 cept by the most remarkable difference in habits of these species, they 

 are to be distinguished by the different shape and curve of the palm 

 margin of the second gnathopod of the males and by the middle (4 th and 

 5 th ) joints of the last pair of pereiopods being expanded in the latter 

 species. As these features have been amply discussed and figured, it is 

 useless to enlarge upon these differences. 



The first gnathopod (f. 1) of the males of the two species is very 

 much alike; I have found no other difference than in the shape of the 

 4 th joint (meropodite), the hind margin of which presents in its middle 

 a marked protuberance in 0. bottae (Chevreux, f. 3), followed by a straight 

 or slightly concave part, which feature does not seem to have been 

 detected by Hoek, though his f. 8, representing this gnathopod, does 

 not show this joint in its full extent. The propodite of this gnathopod 



