314 ME. E. J. MIEKS'S REVISION OF THE HIPPIDEA. 



not easy to trace any resemblance either to the Cancroidea or to 

 the Oxystomata in the form of the mouth and oral appendages. 

 There exists, however, an important characteristic, and one, I 

 believe, not hitherto noted, in the form of the terminal lobe of 

 the exognath of the first pair of maxillipedes, which in the Hippidea 

 is elongated and narrow, as in the Oxystomata, where it is usually 

 applied to the opening of the eiferent branchial channel. In the 

 Cancroidea and OxyrJiyncJia this joint is more or less obtriangular, 

 short, and truncated at its distal extremity. 



Stimpson, in the Report already referred to (Proe. Ac. Nat. Sci. 

 Philad. p. 229, 1858), places the Hippidea in the second section, 

 Schizosomi, of the Anomura. He establishes the two very distinct 

 and natural idim\{\GS,Hippidce and Albuneidce, gives diagnoses of the 

 known genera, and adds two, previously unrecorded, to the list*. 



Geographical Distribution. — The Hippidea inhabit all the 

 warmer temperate and tropical seas of the globe. Bemipes 

 testudinarius, one of the most variable, is also the most widely 

 distributed species, occurring throughout the whole Indo- Pacific 

 region, from the east coast of Africa, along the southern and south- 

 eastern coast of Asia, in Australia, through the islands of the 

 Pacific, to the Galapagos and Cape St. Lucas in California. 

 Another species, R. scutellatus, is found on both the eastern and 

 western shores of the Atlantic Ocean. The majority of the 

 species of the family appear, however, to be somewhat restricted 

 in their range. Those belonging to the family AlhuneidcB are, 

 with two exceptions, restricted to the American continent, where 

 these Crustacea are especially abundant. The only species at 

 present certainly known to inhabit the seas of Europe is Alhunea 

 guerinii from the Mediterranean. 



List of tJie Species of Hippidea. 



Fam. HippiD^. 



Remipes. 

 Names of the Species. Geographical Range. 



1 . R. testudinarius, Latr. Whole Indo-Pacific region. 



„ var. denticulatifrons, „ 



2. R. seutellalus (Fabr.). Florida, West Indies, West coast 



of Africa, Cape-Verd Islands, 

 Ascension Island. 



* Dr. Olaus (' Untersuck. Crust. Syst.' pp. 59-61, Wien 1876) rejects the 

 suborder Anomura, and refers the Hijpjpidea to the Bi-achyura on accoimt of 

 what is known of their development. I regret that I have not yet had an 

 opportunity of studying this important work. 



