REPORT ON THE CRUSTACEA MACRURA. 707 



both genera correspond in form and the oral appendages generally resemble each other. 

 In Typton the branchias, however, number six or seven on each side, namely, a pair of 

 pleurobranchise corresponding with each pan- of pereiopoda, and a pair of arthrobranchias 

 attached to the membranous articulation of the second pair of gnathopoda. 



Geographical Distribution. — Species of this genus have been found in the Medi- 

 terranean by Roux, Costa, Risso, Verany, Lucas, Guerin-Meneville, Heller, and Milne- 

 Edwards. .Roux 1 records Pontonia parasitica from the coast of Morea, and like 

 Pontonia tyrrhena it was found lodged between the valves of a Pinna after the 

 manner of Pinnotheres in the oyster; and it is probable that it is to this Crustacean 

 that Aristotle refers when he says a little Squilla as well as a little crab is found in 

 the shell of a Mollusc. Species, according to Milne-Edwards, have been taken in the 

 Asiatic Seas by Dussumier, off the coast of New Ireland and Vanicoso by Quoy and 

 Gaimard, and at Ceylon by Reynaud. Both Dana and Stimpson found species resident 

 in the shell of Tridacna, the former off Tutuilla, one of the Samoan or Navigator 

 group of islands in the Pacific, and the latter off the Island of Bonin. The species 

 described in this collection was taken from the pearl oyster {Meleagrina ?) in Torres 

 Strait. 



Pontonia meleagrinse (Peters) (PI. CXXIV. figs. 1, 2). 



Conchodytes meleagrinx, Peters, Bericht. d. k. preuss. Akad. d. Wiss. Berlin, p. 594, 1852. 



„ „ Hilgendorf, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 836, 



1878. 



Carapace more than one-half the length of the animal ; dorsally broad and flattened, 

 being wider across the cardiac region than anteriorly or posteriorly. Rostrum dorsally 

 flattened, anteriorly depressed, inferiorly slightly compressed and produced. Frontal 

 margin deeply excavate to form an orbit, the outer canthus of which is defined by a 

 point. There is no tooth corresponding with the first or second antennas. 



Somites of pleon short and dorsally flattened ; the anterior is the broadest and the 

 posterior the narrowest. The fifth somite and telson are wanting. 



Ophthalmopoda short, being about half the length of the rostrum. 



First pair of antennae having the peduncle equal in length with the rostrum and the 

 flagella short, or about half the length of the peduncle. Upper and outer flagellum 

 stout, inner slender. 



Second pair of antennas having the peduncle longer than the scaphocerite, which is 

 broad, sharp pointed, and lanceolate in form. 



Posterior to the oral organs all the appendages of the pereion, excepting the second 

 right pereiopod, are broken off in our specimen. 



Gnathopoda subpediform, having the terminal joints broad, squamous, and reflexed. 



1 Loc. cit. 



