290 ECHIN0DERM8 OF THE BRITISH ISLES 



SaleniidjT. All Saleniids are small forms and all are inhabitants 

 of the deep sea. 



Fig. 164. — Salenocidaris profundi, dorsal side ; half denuded. Nat. size. 

 (After Doderlein, Echinoidea, Deutsche Tiefsee Exped.) 



Fam. Arbaciid^ 



Diagnosis of the family given in the key. 



In European seas this family is represented onl}^ by the genus 

 Arbacia Gray (Syn. Echinocidaris Desmoulins), and only by the 

 species A. lixula (Linn.) (Syn. Arh. pustulosa (Leske), oequitiiber- 

 culata (Blainville)), which occurs in the Mediterranean, off the 

 Moroccan coasts and at the Azores, but is not known to the 

 north of the Gibraltar Strait. It is mainly a littoral form. 

 Another genus, Arbaciella Mrtsn., with only known species Arb. 

 elegans Mrtsn., a very small form with flattened spines, occurs 

 on the African west coast, but is not known to the north of 

 Cape Blanc. There is scarcely any probability of these two 

 species occurring as far north as the British area. 



In the West Indies are found three deep-sea forms of 

 Arbaciids, namely Coelopleurus floridana A. Agassiz, a large 

 form with very long curved and pointed, red primary 

 spines, Podocidaris sculpta A. Agassiz, and Habrocidaris scutata 

 (A. Agassiz), the two latter very small forms, of white colour, the 

 former with 4, the latter with 5, anal plates. Although not 

 hitherto known outside the West Indies, it is not improbable 

 that they may occur also in the N.E. Atlantic deep-sea region. 



