EEPORT ON THE CRUSTACEA MACRURA. 705 



and is armed with numerous spiuules uear the distal extremity ; a prominent one 

 stands at the apex, while at the base there is a series of several transverse rows of short 

 curved hairs, and on the penultimate joint another series of shorter and more distant 

 rows of hairs. Attached to the basisal joint is an ecphysis that reaches beyond the 

 meral articulation of the carpal joint. 



The first pair of pereiopoda is short and stout, it has the carpos broad, short, and 

 lunate, in the hollow of which the propodos rests when extended ; the propodos has the 

 inferior distal or polliciform angle stout and tipped with a brush of hairs, while the 

 dactylos is short, curved, and thick, but narrower than the pollex, and like it distally 

 furnished with a brush of hairs that are ciliated at their extremity and do not equal the 

 joint in length. The second pair of pereiopoda is longer than the first ; the carpos and 

 preceding joints are cylindrical and slender, the carpos being long and not distally lunate. 

 The chela is formed as in Atya, but the propodos is more robust at the base, and the 

 pollex and dactylos are tipped with a shorter brush of hairs. The third pair of pereio- 

 poda is slender, slightly longer than the second, and slightly more robust, particularly at 

 the meral joint, which is armed on the posterior margin with three strong spinules. The 

 carpos is long, with the margins subparallel, the posterior margin being armed with 

 four small spinules and a fifth and larger one on the side ; the upper distal angle projects 

 over the propodal articulation ; the propodos is nearly twice the length of the carpos, 

 cylindrical, and armed on the posterior surface with a double row of spinules that increase 

 in size as they approach the dactyloid articulation ; the dactylos is slightly curved, armed 

 with four or five spinules on the posterior margin, and terminates in a strong unguis. 



The length of the living specimen, judging by what is preserved of it, must have 

 been about 20 mm., or about the same length as the specimen recorded by Milne -Edwards. 



It is desirable to notice that Milne-Edwards, in his description of Caridina typus, 

 says that the rostrum is " aigu, mediocre, . . . . et arme en dessous de trois petites 

 dents." The carapace, with the rostrum, has been preserved in our specimen, but 

 separated from the rest of the animal, and it shows the three little teeth corresponding 

 with Milne-Edwards' description as well as with the description of Atya serrata from 

 the Cape Verde Islands. 



Pontonia, Latreille. 



Pontonia, Latreille, Regne Anim. de Cuvier, ed. 2, torn. iv. p. 96. 



,, Roux, Mem. class, crust. Salicoques, p. 26. 



,, Milne-Edwards, Hist. Nat. Crust., torn. ii. p. 358. 



„ de Haan, in Siebold's Fauna Japonica, Crust., p. 75, tab. 0. 



„ Dana, U.S. Explor. Exped., Crust., p. 570. 

 Conchodytes, Peters, Bericht. d. k. preuss. Akad. d. Wiss. Berlin, p. 588, 1852. 



The species on which this genus was founded by Latreille, and confirmed by Milne- 

 Edwards, was that which was described by Risso as Alpheus tyrrhenus. According to 



(ZOOL. CHALL. EXP. — PART LII. — 1887.) Fff 89 



