ECHINOIDEA 289 



Fam. SALENIIDiE 



Diagnosis of the family given in the key. 



This family, which was very flourishing during the Jurassic 

 and Cretaceous periods, has but few living representatives. These 

 latter have been divided into two genera, namely Salenia Gray, 

 with ambulacral plates compound, made up of two primary 

 plates, and Salenocidaris A. Agassiz, with ambulacral plates 

 simple, excepting one or two at the peristome. 



Of the genus Salenia, thus restricted, no species have been 

 found in the N.E. Atlantic, but one, S. P alter soni A. Agassiz, 

 occurs in the West Indies and might perhaps also be found in the 

 N.E. Atlantic ; it is easily recognisable by its primaries, which 

 are banded with red and white. ^ Of the genus Salenocidaris, two 

 species have been found in the N.E. Atlantic, viz. S. profundi 

 (Duncan) (Syn. Salenia hastigera A. Agassiz), known from the 

 Faroe-Iceland banks (63° 9' N., 13° 27' W., 880 m., "Michael 

 Sars "), from the Bay of Biscay and the Azores to Tristan 

 d'Acunha, and also recorded from various places in the Indo- 

 Pacific ; bathymetrical distribution, ca 180-3380 m. ; S. vari- 

 spina (A. Agassiz), found off the Azores, 1800-3015 m. 

 (" Challenger "), also recorded from the West Indies and off 

 Ascension ; bathymetrical distribution, 630-3015 m. These two 

 species are thus distinguished : 



Usually 5 (3-6) larger ambulacral tubercles in. each series on the 

 oral side. Valves of tridentate pedicellarise strongly curved, 

 indented near tip ; test rarely exceeding 10 mm. horizontal 

 diameter ..... 5. varispina (A. Agass.) 



Usually 3 (2-4) larger ambulacral tubercles in each series on the 

 oral side ; valves of tridentate pedicellarise nearly straight ; 

 up to 16 min. horizontal diameter of test S. profundi (Duncan) 



The species Salenocidaris profundi (Fig. 164), occurring both 

 to the north and the south of the British area, may be expected 

 almost with certainty to occur also off the west coast of Ireland 

 and Scotland. 



Nothing is known about the biology and development of the 



^ Another species with similar red-banded spines, S. phoinissa A. Agass. 

 and H. L. Clark, occurs off S. Africa. For the characters distinguishing 

 these species see A. Agassiz and H. L. Clark, Hawaiian, a.o. Pacific Echin. 

 Salenidce . . . Diadematidce, p. 54 



