114 Bulletin Yanderbilt Marine Museum, Yol. Y 



Leptodius exaraUis variety Rathbun, Trans. Linn. Soc. London, ser. 



2, vol. 14, p. 215, 1911. 

 Leptodius exaratus variety acutidens Rathbun, Bull. U. S. Nat. Mus., 



vol. 52, p. 310, 1910. — Edmondson, Bull. B. P. Bishop Mus., vol. 5, 



p. 14, 1923. 

 Xantho (Leptodius) exaratus Alcock, Journ. Asiatic Soc. Bengal, 



vol. 67, pt. 2, 118, 1898.— Calman, W. T., Trans. Linn. Soc. Lond. 



Zool. ser. 2, vol. 8, p. 6, 1900-1903.— Laurie, R. D., Ceylon Rept. 



Pearl Oyster Fish., vol. V, p. 402, 1906. 

 Xantho exaratus Doflein, Abh. Math.-Phys. K. B. Akab. Wiss. Bd. 



21, p. 660, 1902.— ScHENKEL, Verh. Naturf. Ges. Basel, Bd. 13, 



p. 575, 1902. 



Leptodius crassimanus A. Milne Edwards. 



Plate 59. 



Type : The type of this species was collected at New Caledonia and 

 deposited in the Paris Museum. 



Distribution : New Caledonia, (A. M, Edwards) ; Port Denison, 

 Port Molle, Port Curtis, Australia, (Haswell) ; Trincomali, Ceylon, 

 (Muller) ; Noordwachter Island, Edam Island, Java; Pontianak, N. W. 

 Coast of Borneo; Batavia Bay; Poeloe Samaoe, Malay Archipelago, 

 (de Man) ; East Australia and Australia, (Ortmann) ; India: Anda- 

 mans, Karachi, Galle, (Alcock) ; Apia, Samoa, (Boone) ; Hawaii: 

 Honolulu, Waialau, Oahu, (Rathbun) ; Fanning Island, (Edmond- 

 son) ; Somerset, Malaysia, (Nobili) ; Massaua, Red Sea, (Balss). 



Material examined : One male taken on the reef at Apia, Samoa, 

 Sept. 3, 1931. 



Technical description : This species is easily distinguished by its 

 very narrow quadridentate frontal margin from its near allies, L. 

 sanguineus (H. Milne Edwards) and L. exaratus (H. Milne Edwards). 



L. crassimanus is about the same size as the above mentioned spe- 

 cies but has its carapace much more convex anteriorly; the well-de- 

 fined regions are more convex and their fewer aerolae are also more 

 convex. The frontal border is narrowed, bilaminate, with the frontal 

 margin sinuous, the inner lobe well separated from the outer by a 

 deep concavity; the outer lobe is in turn separated from the orbital 

 angle by a deep notch. The superior orbital margin is circumscribed 

 but not very tumid and is marked by two closed sutures on the upper 

 margin and one below. The anterolateral margin is cut into four 



