66 Prof. P. M. Duncan on the Salenidge. 



defined swelling that cover the plates more or less. Sometimes 

 radial lines and radial swellings exist ; but all the ornamenta- 

 tion is very indistinct. There is not a trace of a granule or of 

 a tubercle's base on the disk. 



The larger specimens of this interesting species are y^j inch 

 or slightly less in breadth at the ambitus, and t^ to -j% inch in 

 height. It is a fine form of Salenia, with all the characters of 

 the Cretaceous species, except the distribution of the pores in 

 the ambulacra. In the older Salemce there is a pair of 

 pores to each ambulacral tubercle, and one intermediate ; or, 

 in other words, two pairs are in relation to each tubercle. 

 The Salem'a described by Prof. Tate has but one pair. This 

 is the case with the recent species of Salenida3, so far as is 

 known. The drawing of a form by Sir Wy ville Thomson 

 does not give the required information ; neither does the 

 context. 



The specific distinction of Salem'a tertiaria, Tate, which 

 relates to the number of primary tubercles (in all stages of 

 their growth) in the interambulacra, allies it with the recent 

 forms more than with the Cretaceous ; and the comparative 

 flatness of the apical rim separates it, with the character just 

 mentioned, from the Saleaia fetalifera^ Agassiz (1838), so 

 common formerly in the Upper Greensand and Chalk Marl of 

 this country. The contour of the test of the Australian form 

 is between that of Salenia geometrica^ Agassiz (1838), of the 

 Upper White Chalk, and that of Salenia petalifera ; but it is 

 not so high as the first in relation to its breadth. But the 

 Upper-Chalk form has as many primary tubercles as the 

 Tertiary species. 



Salenia from the Eocene. 



Cotteau described a well-marked species of Salenia from 

 the Lower Nummulitic formation of Biarritz in 1860. His 

 interesting description did not escape the research of Dr. 

 Wright, who refers to the fact in his monograph on the 

 British fossil Echinodermata from the Cretaceous formations 

 (Pal. Soc. vol. i. pt. 4, p. 149, 1871). 



The following is a rendering of M. Cotteau's description 

 (Rev. et Mag. de Zoologie, Mai 1860, p. 222, " Echinides 

 Nouveaux ou peu connus," par M. G. Cotteau, plate xiii. 

 tigs. 11-14) :— 



Salenia Pellati^ Cot. 



The test is small, short, circular in outline, slightly swollen 

 above, and almost flat on the actinal surface. The interam- 

 bulacra are broad, and are ornamented with two rows of tuber- 



