ECHINODISCUS BISPEKFOllATUS. 71 



Antoro-laU'ral petals disliiictly loiifjcr llian posloi-ior; widtli nf lest exceeds its 

 length. 



l.iiiiuleslongcr than longest petal hispcrfomlus. 



l.uiiules shorter than shortest petal bis pcrf oral u.i var. truncatus. 



Echinodiscus auritus. 



Leske, 177S. Add. ad Klein, p. 138. 



Plate 125, figs. 9, 10. 



The biphyllous pedicellariae have broad valves (PI. 125, fig. 9) with rather 

 flat blades, coarsely serrate on the margin. The bidentate are even more char- 

 acteristic having the blade narrowed at base, while the basal part of the valve 

 has the sides nearly parallel (PI. 125, fig. 10). The biphyllous valves are .07-.09 

 mm. long, the bidentate .10-.50 mm. No ophicephalous pedicellariae were 

 seen. 



The distribution of auritus seems to be chiefly in the western part of the 

 Indian Ocean and in the Red Sea, but it is also known from several localities 

 in the Dutch East Indies. 



Echinodiscus tenuissimus. 



Lobophora tenuissima Agassiz and Desor, 1847. Ann. Sci. Nat., .ser. 3, 7, p. 136. 



Echinodiscus tenuissimus Gray, 1855. Cat. Rec. Ech., pt. 1, p. 20. 



Echinodiscus laevis A. Agassiz, 1872. Rev. Ech., pt. 1, p. 113. (From Klein, 1734). 



Plate 125, figs. 11, 12. 



All three kinds of pedicellariae occur. The ophicephalous have valves 

 (PI. 125, fig. 12) only .10-.13 mm. long, exclusive of the loop which in the largest 

 valve adds .07-.0S mm. more. The biphyllous valves are only .05-.06 mm. long. 

 The bidentate valves (PI. 125, fig. ./i) are .35-.40 mm. long; the blade is narrow 

 with parallel sides while the basal part has sloping or oblique sides. 



The distribution of tenuissimus is in the East Indian region from Japan 

 southward to New Guinea. 



Echinodiscus bisperforatus. 



Le.ske, 1778. Add. ad Klein, p. 132. 



Pediceflariae are very rare and only tridentate were found; their valves 

 resemble those of tenuissimus (PI. 125, fig. .?/). The distribution of this species 

 seems to coincide with that of auritus. 



