114 AUSTRALIAN MA1AC0STBACA. 



Sub-Family Hymenicince. 



Body very much depressed, sub- orbicular, or sub-triangular, 

 slightly produced, often, rostrate, anteriorly. Second joint of 

 the external maxillipedes more than half the length of the third 

 joint. [I).-] 



G-enus Hymenosoma, Leach. 



Carapace depressed, usually sub-circular in outline, flat above. 



The sub-division of this sub-family into the genera Hymenosoma, 

 Hymenicus, and Halicarcinus, appears to be unnecessary, and 

 based on extremely slight points of distinction, and I have 

 therefore placed all the species under Leach's original genus. 



209. Hymenosoma planatum. A.M. 



Cancer planatus, Eabr., Bnt. Syst., ii., p. 446 (1793). 



Leucosia planata, Fabr., Ent. Syst., Suppl, p. 350 (1798). 



Hymenosoma Leachii, Gruerin, Icon., pi. x., fig. 2, Voy. Coquille 

 ii., p. 22 (1828). 



THymenosoma tridentatum, Jacq. and Luc, Voy. Pole Sud, 

 Zool., iii., p. 60, pi. v., fig. 27 (1853). 



Halicarcinus planatus, "White, Ann. Mag. Nat. Hist., xviii., 

 p. 178, pi. ii., fig. 1 (1846). 



Halicarcinus ovatus, Stimpson, Proc. Acad. Nat. Sci. Philad., 

 p. 109 (1858). 



Carapace quite flat above, with a transverse groove separating 

 the gastric from the cardiac regions, and a longitudinal groove 

 on each side of these regions. Antero-lateral margins with two 

 small acute teeth. Anterior legs of the male very much enlarged, 

 hand smooth and swollen, fingers straight, with a space between 

 them when closed. Length ^ in. ; breadth | in. 



Port Jackson ; Port "Western. 



The Flamene Mathai of Milne-Edwards (Ann. Sci. Nat. 

 (3 ser.) xx., p. 223, pi. xi., fig. 4, and Hist. Nat. Crust., ii., p. 35) 

 is probably the young male of this species. It is quite distinct 

 from the Hymenosoma Matlicei of Desmarest (Consid., p. 163), 

 which is described as having the form of an equilateral triangle, 

 with the anterior angle (rostrum) a little rounded, As to which 



