82 THE TERTIARY FOSSIL ECHINOIDEA 



lini (de Loriol, Pal. Suisse: ' Descr. des Oursins fossiles de la Suisse'). But here, 

 again, the sharp projecting ambulacral lip is not seen in the Miocene form. 



There is a furrowing of the horizontal suture-edges of the interradial plates, which 

 recalls the Temnopleuridee, but no pits or deep furrows are to be seen ; and the like 

 ness is increased by the nature of- the triplets, which resemble those of Salmacis. We 

 include the form in a new genus. 



Suifamily TBIPLECHINID^, A. Agassie. 



Gems GRAMMECHINUS* gen. nov. 



The test is thin, rather depressed, swollen at the ambitus, flat or incurved actinally, 

 low and conical abactinally. Marginal outline slightly pentagonal or nearly circular. 

 .Ambulacra with pairs of pores in regular triplets from apex to peristome ; pla,tes with 

 from one to three tubercles on them. Interambulacral plates broad and low, carrying 

 from one to eight tubercles, the number diminishing towards the apex. Tubercles of 

 both series neither perforate nor crenulate, small ; secondaries in lines above and below 

 the primaries, forming ridges, with the depressed horizontal sutural line between the 

 two series. Vertical ridges of small tubercles, more or less linear in shape, may be in 

 relation with the largest tubercles. Actinostome moderately large, rather pentagonal ; 

 cuts moderately developed ; ends of ambulacra moderately wide. . (Apical system 

 wanting.) 



1. GRAMMECHINUS KEGULARis, Bwncan & Sladen. Plate XIII, Figs. 7, 8. 



The test is circular or slightly pentagonal in marginal outline, tumid at the ambitus, 

 conical and rather depressed abactinally, slightly incurved actinally around the rather 

 large peristome, which is rather pentagonal in outline. The ambulacra are broad, and 

 at the ambitus are one half the breadth of the interradium ; more abactinally the 

 ambulacrum is two thirds the width of the interambulacra, and nearer the peristome the 

 relative breadth becomes rapidly less. The ambulacral plates are tall in relation to 

 their breadth near the peristome, and carry at first one and then, more abactinally, two 

 tubercles. At the point of greatest breadth the plates are broader in relation to height 

 and carry three tubercles. Each plate has three pairs of pores, forming a curved line. 

 The pores are large and separated by a projection ; and the pairs, also well separated, 

 have a granular, or plainly linear, raised structure between them. Immediately 

 actinally to the second pair of the triplets is a small tubercle, and there is a smaller one 

 on a line with and externally to the first pair. The tubercles of the ambulacra are broad 

 at their base and have a distinct mamelon, which is neither perforate nor crenulate. 

 The tubercle nearest the pores is the largest, and is crossed by the sutural lines of the 

 poriferous plates. The remaining tubercles are larger than those immediately beyond 

 the line of pores, and all have a mamelon. 



* ypaix/xri, a line. 



