ASTACI DE A. 517 



(riangulatum. Antennae extern inter se fere contiguas. Oculi fere in medio 

 inter antennas internas et angulos cephalothoracis externos. Branchiae 21. 

 Species, P. antarcticus et P. Parrce (Ibacus antarcticus et I. Parraa, Auct.) 

 G. 5. IBACUS, Leach. Rostrum bilobatum. Antennas extern* inter se paulo 

 remotae. Oculi versus rostrum insiti. Branchiae 21. Species, I. Peronii, I. 

 ciliatus, De Haan, et /. novemdentatus, Gibbes. 



The species mentioned are given by Milne Edwards, in his Crustaee's, ii. 279289, 

 excepting .Sc. Haanii of von Siebold, which is described in Faun. Japon., 152, pi. 38, 

 f. 1, and by Berthold, in Gbtt. Gel. Anz., 1845; Sc. Sieboldi, De Haan, Faun. Japon., 

 p. 153, pi. 36, f. 1 ; Ibacus ciliatus, von Siebold, Spicilegia Faunas Japonicae, 15, and 

 Faun. Japon., 153, pi. 36, f. 2; and I. novemdentalus, Gibbes, in. Proc. Assoc. Amer., 

 Charleston Meeting, 1850, iii. p. 193. 



IBACUS ANTARCTICUS (Rwnph.} 

 Plate 32, fig. 6, animal, natural size. 

 Upolu, Navigator or Samoa Group. 



Length, seven and three-fourths inches ; breadth across the line of 

 the eyes, three and two-thirds inches ; between the eyes, one and 

 eleven-twelfths inches. Colour, yellow or smoky yellow, clouded 

 with smoky brown and some spots of carmine ; around the eye car- 

 mine. Last abdominal segment, deep ochre-yellow and short hirsute. 

 Eye situated just exterior to base of outer antennae. Surface of body 

 without spines, squamato-tuberculate. Carapax with seven profound 

 incisions laterally, each hirsute within ; second incision deepest. 

 Lateral portions of second and third abdominal segments extend 

 outward and curve forward, with two deep incisions ; the following 

 one also extends outward, and has a deep incision, but its extremity 

 is not anterior to its front margin. Legs projecting but little beyond 

 the carapax. 



ARCTUS VITIENSIS. 



Carapax subtilissimis plumulis pubescens, spind pone medium frontis et 

 alterd gastricd armatus, versus orbitam utrinque subcarinatus et 12- 

 dentatus. Antennae internee nudiusculce, articulo basis penultimo fere 



130 



