[From the American Journal of Science and\Arts, Vol. 29, Jan. 1860. 



6. Sketch of a revision of the genera of Mithracidce ; by Wm, Stimp- 

 son. — The old genus Mithrax was divided into three groups by Milne- 

 Edwards, (Hist. Nat. des Crust,, i. 318), Mithrax triangulares, M. trans- 

 vcrsaux, and M. deprimes. These groups are now considered of generic 

 value. For the first group De Haan has proposed the name Dione, which 

 cannot however be adopted, as it was previously applied to a genus of Lepi- 

 doptera, by Hiibner. It is also used for a bivalve shell. To the third 

 group "White gave the name Mithraculus, which was adopted by Dana. 



In the Proceedings of the Zoological Society of London, 1847, p. 222, 

 Mr. Adam Whitegives a wood-cut of a maioid crustacean, to which lie 

 applies the name Schizophrys, with the following description : "Carapax 

 oval, depressed, somewhat attenuated behind ; beak deeply cloven ; upper 

 orbit deeply cloven, with a strong tooth in the middle of the cleft guilder 

 orbit an elongated appendage on the inside, with two teeth at the end. 

 Tale of male with V joints, the sides nearly parallel. Fore-legs "shortest. 

 Fingers without teeth.'' This genus, in the catalogue of the British Mu- 

 seum, is placed between Othonia and Peficera. But if we consider that 

 by the "elongated appendage on the inside" of the orbit, Mr. White prob- 

 ably means the basal joint of the external antennae, and observe how 

 closely the figure corresponds to young crabs belonging to l>e llaan's ge- 

 nus JDioru . a is unavoidable that SchUuphrys is really synon- 

 ymous witli the* Mithrax triangulares of Milne-Edwards, and as such we 

 here adopt it. In the following synopsis new characters are introduced ; 

 some new genera are described, and a list given of the species known up to 

 the present date. 



A. Maxillipedis externi merus margine antico integer. 

 MmiKACui-us, White. (Mithrax, pro parte, De Haan, Fauna Jap. Cr, 



82.) Carapax depressus, nistro brevissirao vel nullo. — M. sculptus, (M.- 

 Edw.,) M. nodosus, (Bell,) M. denticulatus, (Bell,) M. coronatus, (Herbst.) 

 M. cinctimanus, Stm. 



B. Maxillipedis externi merus angulo antero-interno excisus, ad palpum 

 incipiendum. 



a. Frons angusta. Orbitae parvae, profunda?, oculos paene operientes^ 

 Mithrax, Leach. Carapax plus minusve transversus. Orbita multifissa, 

 margine dentibus vel tuberculis armata. 



1. Antennae externa? articulus basalis spinis tribus armatus. — M. verru- 

 cosus, M.-Edw., M. aculeatus, (Herbst.) 



2. Antennae externae articulus basalis spinis duabus armatus. — M. spi- 

 nosissimus, (Lamk.), M. hispidus, (Herbst,) M. ursus, Bell, M. rostratus. 



