252 THE FOSSIL ECHINOIDEA 



Unfortunately d'Archiac and Haime described this species from a very imperfect 

 specimen, and necessarily limited the number of smaller tubercles in relation to the 

 large primaries of the interradia. They state there are seven large tubercles in each 

 vertical series flanked externally by a row of five smaller, some unequal granulations 

 intervening between them. 



Desor gives a figure of this species (Synopsis des Echinides Fossiles, plate xvi, 

 figs. 4-6). The specific distinctions are clearly given : — 1. The pentagonal and depressed 

 shape of the test. 2. The protuberance of the ambulacra. 3. Well-developed tubercles ; 

 primaries in the interporiferous area up to the beginning of the ambulacrum. 4. 

 Actinally, a distinct row of secondary tubercles, large in size, between the rows of the 

 primaries of the interradia and the poriferous zone of the ambulacra. This row 

 extends in a single vertical series of secondary tubercles to the ambitus, and there is 

 a smaller, but equally linear series, reaching to the abactinal system. 5. Primary 

 tubercles in the interradium above the ambitus, two or they may be three in number, 

 small, and not extending on the wide bare median space. 



There are two types of this species in the Nari series. One is as depressed as 

 Desor's type, and the other is a little higher. The vertical row of secondaries, much 

 smaller than the interradial primaries, and of about the size of the small ambulacral 

 primaries near the radial (ocular) plates, is very distinct and characteristic. 



The apical system is large and the anal rim projects upwards slightly ; there are 

 five or six large miliaries in a row on the madreporite at the rim-edge, and about three 

 to five on each of the other basal (generative) plates, either in a curve or straight line. 

 A knob larger than these miliaries is on each basal plate. The basals (generative plates) 

 are large and unequal ; the madreporite is much the largest, and that of the inter- 

 radium No. 1 (Love n) is a little smaller, and the others are decidedly smaller. They 

 have a blunt angular process ad orally ; and in one specimen the generative pores, large 

 and open, are near the outer margin of most of the plates, but they are central in another. 

 The radial (optic) plates are sunken, not very large, and have the outer or actinal 

 margin with a reentering curve. On the plates are miliaries and ridges, in an arch 

 which completes, as it were, the ambulacral petal, and also a row of granules. There 

 is a central projection on the adoral edge which separates the optic foramen into two, 

 which are hidden. The anal opening is large and oblique, its long axis passing through 

 interradium 3 and ambulacrum I. (Loven). 



There are twenty- two primary tubercles in each ambulacrum, and they increase in 

 size from the peristome to the ambitus, and diminish to the abactinal end. The 

 smallest tubercle is close to the radial (optic) plate. The ambulacra are very prominent 

 above the ambitus, but are not more projecting than the interradia, when the test is seen 

 from the actinal surface. The narrowness of the ambulacra is evident, and the tubercles 

 are close ; there is an incomplete row of large miliaries along the median suture, and 

 large shallow pits are at the sutural angles in the median line near the peristome. The 

 peristomial cuts are small ; and the width of the peristomial end of the ambulacra is 

 equal to that of the interradia in that position. 



The pairs of pores of the ambulacra are in slightly curved triplets, from close to 



