12 ECIIINODERMA OF THE INDIAN MUSEUM, PART VII. 



forms; there are only a few (possibly in reality no) species not found elsewhere, 

 and these are not greatly different from others either to tlie east or to the west. 

 The partial '' explosion " of the faunal units seen in northern Australia and 

 southern Japan is totally absent here. 



On going westward from Ceylon we hnd that the fauna undergoes a curious 

 segregation of its component genera and sjiecies, one section extending northward 

 along the coast of Persia and Arabia to the Red Sea, and the other southward 

 and westward to south-eastern Africa, reaching the region from Mombasa south 

 to Cape Colony. 



In the Red Sea region we find a fauna composed of 18 species, representing 

 1(5 genera distributed among 11 families; these are: Comasteridse — Comanthus 

 (Vania group); Himerometridse — Craspedometra, Heterumetra; Stephanome- 

 tridffi — Stephanometra ; Mariametridse — Dichrometra ; Colobometridae — Decame- 

 tra, Colobometra, Oligometra ; Tropiometridse — Tropioinetra ; Thalassometridaj — 

 Tlialassomeira ; Charitometridae — Pachylometra ; Antedonidw — Iridometra, Thau- 

 iiiatometra, Cychmetra ; Pentametrocrinidas — Pentametrocrinus ; Bourgueticrini- 

 d te — Bhizocriniis . 



The genera Himeromeira and Cyllometra reach the Persian GuK, but not the 

 Red Sea. 



All of these genera are widely distributed, none being cliaracteristic of the 

 region; but of the species 13 out of the 18 are found nowhere else. Another 

 interesting feature is that, with one exception, each genus is only represented 

 here by a single species which, when characteristic, is smaller than the average 

 of the species in the same genus elsewhere. 



Along the south-eastern coast of Africa, from Mombasa southward to the 

 Cape, including Madagascar, Mauritius, and the other outlying islands, there 

 exists a richer fauna. Here are found 22 species distributed among 18 genera, 

 which, strictly speaking, should be considered as four more than the number in- 

 habiting the Red Sea region , for no opportunity has offered for determining the 

 presence of Thaumatometra , Cyclometra, Rhizocrinus, or Pentametrocrtnu^ here, 

 though doubtless they occur. These 18 genera represent nine families, as follows : 

 (Jomasteridaj — Comatella, Capillaster, Gomissia, Comanthun (Vania, Bennettia) ; 

 Himerometridge — Amphimetra , Craspedometra, Heteromeira ; Stephanometridae — 

 Stephanometra ; Mariametrida3 — Dichrometra ; Colobometrid* — Genometra, 

 Decametra, Oligometra ; Tropiometridse — Tropiometra ; Thalassometridse — Thalasso- 

 metra, Cosmiometra ; Charitometridse — Pachylometra ; Antedonidae — Irido- 

 metra, Perometra. Of the 22 species 18 are confined to the region while four occur 

 in Ceylon, three of these ranging also much further east. All of the genera are 

 very widely spread throughout the East Indian region, and all of the species are 

 related to corresponding species in the East Indies, there being no widely diver- 

 gent forms as in northern Australia. Comanthus (Bennettia) wahlbergii, which 

 occurs about the southern extremity of Africa and as far north as Natal, is 



