50 P. M. DUNCAN ON THE ECHINODEEJVTATA OF THE 



less developed than the others ; and those of the inner or posterior 

 zones of the lateral posterior ambulacra are few in number towards 

 the ambitus, to which, however, they extend. The ocular pores 

 are well developed, and a miliary granulation covers the test between 

 all the pores and the interporiferous areas, a few scattered tertiary 

 tubercles being there also. The tuberculation is small, and tubercles 

 of the third order are the largest on the upper surface. They 

 increase in number towards the ambitus, and are surrounded by a 

 sunken scrobicule surrounded by miliaries. The keel is distinct, 

 slightly angular, and reaches backwards so as nearly to overhang the 

 ambitus. 



The concave actinal surface has a large sunken mouth, a plain 

 band reaching from it posteriorly, and a distinct tuberculation at 

 the edge of the test. 



Length of specimen 1-^ inch, breadth ly 8 ^-, height ^-. 



Locality. — No. 5 Upper Coralline Beds, Castle Cove, near Cape 

 Otway. 



The resemblance of this species to Rliynclwpygns paci/ictis, Ag. 

 (Eev. Ech. Part i. p. 153 and Part iii. p. 554), is very decided in 

 some points ; but it differs from it and from the species from the 

 Caribbean Sea by having an elongated apical system, and in the 

 separated apical ends of the lateral and posterior pairs of ambulacra. 

 This Dysasterian peculiarity resembles that of Hyboclypus, which 

 may be said to be a Galerites with an elongated apical system, thus 

 uniting this last genus to Anancliytes. The Australian Lower 

 Cainozoic Rliyncliopygiis is unlike all the other species of the genus 

 in this special peculiarity. The genus is represented in the 

 Gault, in the uppermost Cretaceous rocks, and in the Tertiary tuff of 

 Guadeloupe ; and the recent forms are from the Caribbean and the 

 Pacific coast of America. Were it not for the strong generic 

 resemblance of the new species, the nature of the curious and 

 suggestive apical system might determine the formation of a new 

 genus ; but it is perhaps most advisable to retain the form where 

 it is placed, so as to make it a passage species from one great group 

 to another. 



Genus EcmNOBRissrs, Breyn, 1732. 



JYucleoIites, Lamk. (part.) . 



Echenobrissus at7steali^;, sp. nov. Plate III. fig. 11. 



The test is depressed and stout, and the outline of the ambitus is 

 elliptical. Seen from above the posterior end is slightly produced, and 

 the anterior is rounded. The vertex is central, and the apical system 

 is anterior to it. The petals are lanceolate and narrow ; the anterior 

 extend rather more than halfway down the test ; the posterior 

 are about the same length ; and all are open. The poriferous zones 

 are of uniform breadth ; and the interporiferous space is nearly of 

 the breadth of one of the zones : it is very slightly raised so as to 

 prevent the ambulacra being flush with the test. The pores are 

 subequal ; those of the inner row are round, whilst those of the 





