1898.] A. Alcock — Cardiological Fauna of India. 69 



following Clans, the Corystoidea. Now undoubtedly several of the 

 forms included under the Corystoidea have very close relations with 

 Cancer and Pirimela ; and if Cancer and Pirimela are regarded as typical i 

 Catameto pes then such (Corystoid) forms as Atelecyclus and HypopeU 

 tarium may also be classed as Cyclometopes. 



In this preliminary paper I prefer not to take Cancer as an ideal 

 Cyclometope, and to leave the Corystoidea for future consideration. 



The Cyclometopa of Ortmann includes the family Parthenopidse, 

 which in this series of papers has, in accordance with the views of 

 other authors, been considered with the Oxyrhyncha ; and also the 

 Corystoid genera Atelecyclus and Hypopeltarium, the Cancrine affinities 

 of which have been admitted. I cannot, however, think that the 

 removal of the Parthenopidse from their long approved position, as 

 Oxyrhynchs showing a connexion between that type and the Cancrine 

 type, serves any useful purpose. 



For the purposes of this paper the Cyclometopa are divided into 

 the following families : — • 



I. Cancridae, in which the fold of the antennules is longitudinal 

 or obliquely longitudinal, and the anterior boundary of the buccal 

 cavern is somewhat indefinite, being more or less overlapped by the 

 external maxillipeds. 



Of this family, of which Cancer and Pirimela are types, no repre- 

 sentative is known in the Indian Seas. 



II. Xanthidae, in which the fold of the antennules is transverse 

 or obliquely transverse, and the anterior boundary of the buccal 

 cavern is raised and sharply defined, so that the external maxillipeds 

 commonly shut close against it unless they fall short of it. 



III. Portunidw, in which the fifth pair of legs is peculiarly modified 

 for swimming and usually has the propodite and dactylus singularly 

 broad thin and paddle-like. 



IV. Telphusidae, in which the form is Grapsoid, the branchial 

 regions being much dilated. The members of this family inhabit fresh 

 water and, sometimes, damp jungle. 



The present paper refers to the family Xanthidse. 



Family XANTHIDSE. 



Canceriens arquds et quadrilateres Milne Edwards, Hist. Nat. Crust. I. 369. 



Cancridae (exc. Cancrinx et ?Polydectinse) and Eriphidee (exc. Oethrinx) Dana, 

 U. S. Expl. Exp., Crust., pt. I. pp. 147, 228. 



Canceriens (exc. Oethra, Cance'rides et Pirimelides) A. Milne Edwards, Nouv. 

 Archiv. da Mus. I. 1863, pp. 177-182. 



Cancridas (exc. Cancer), Miers, Challenger Brachyura, p. 10G. 



Xanthini (exc. Thiidx), Ortmann, Zool. Jahrb. Syst. VII. 1893-94, p. 412. 



