206 PERCY SLADEN TRUST EXPEDITION 



36. Portunus (Achelous) orbicularis (Richters). 

 Neptunus (Achelous) orbicularis Alcock (4), p. 47. 

 Cargados Carajos, 30 fms., Sta. B 3 ; 1 $, 2 juv. 



2, C. 1. 27 mm., C. b. 34'2 mm. 



37. Portunus (Xiphoneetes) longispinosus (Dana). 

 Neptunus (Hellenus) longispinosus Alcock (4), p. 40. 



Salomon, 1 £, with the appearance of having been in a fish stomach. Providence, 

 39 fms., Sta. D 1 ; 1 $, 2 ?. Seychelles, 31 fms., Sta. F 2 ; 2 $ : 34 fms., Sta. F 8 ; 2 $. 



38. Portunus (Xiphoneetes) macrophthalmus Rathbun. 



Portunus (Xiphoneetes) macrophthalmus Rathbun, 1906, p. 871, text-fig. 31, pi. 12, 



fig. 5. 



Cargados Carajos, 30 fms.*, Sta. B 9 ; 1 ?. Seychelles, 31 fms., Sta. F 2 ; 2 $. 



39. Callinectes alexandri Rathbun (Plate 17, fig. 4). 



Callinectes alexandri Rathbun, Mem. Mus. Comp. Zool., xxxv. 1907, p. 61, pi. 2, 

 fig. 1, pi. 9, figs. 3, 3 a, 3 b. 



Cargados Carajos, 30 fms., Sta. B 23 ; 1 $ small, but mature. C. 1. 25"3 mm. (approx.), 

 C. b. 53-3 mm. 



This species was based on two young specimens from Tahiti and Fiji ; the specimen 

 from the Indian Ocean is considerably larger, without being full grown, and, when taken, 

 was about to moult. It presents some differences from the type, differences which it 

 seems best to regard as due to age until more material is available. 



(1) The carapace is narrower and the lateral spine shorter. (Compare pi. II, fig. 1, 

 loc. cit., with the figure given here.) 



(2) The granulation on the carapace is denser. 



(3) The lateral teeth are blunter and less like saw-teeth. Teeth 2 to 6, inclusive, 

 are similar, their posterior margins about 1^ times as long as their anterior margins, 

 tips blunt ; tooth 7 has the posterior margin about 1^ times as long as the anterior, 

 tip blunt ; tooth 8 is narrower, sharp, anterior margin deeply concave, and having the 

 same length (across the chord) as the posterior margin ; lateral spine 3^ times as long as 

 the preceding tooth, its axis transverse. 



(4) The last two segments of the abdomen are a little more elongate than in 

 pi. IX, fig. 3 a, loc. cit. The appendages of the first segment (which were undeveloped in 

 the type) have straight extremities and reach to the terminal fourth of the sixth segment. 



40. Charybdis erythrodactyla (Lamarck). 

 Charybdis erythrodactyla Rathbun, 1906, p. 872, pi. 4. 

 Salomon ; 1 $. Amirante ; 1 $. 



41. Charybdis paucidentata (A. Milne Edwards). 



Goniosoma paucidentatum A. Milne Edwards, Nouv. Arch. Mus. Hist. Nat., Paris, x. 

 1861, p. 381, pi. 35, fig. 3. 



* May have been swimming at the surface. 



