AUSTRALIAN CAIN0Z0IC (TERTIARY) DEPOSITS. 61 



the floscelle ; and the pores represent an absent boss which is replaced 

 by the slit. 



The ornamentation of the plastron (actinal) is very beautiful 

 (PI. IV. fig. 7). There is a triangular space in front of the trans- 

 verse part of the subanal fasciole which has a slight median and 

 central projection covered with small tubercles ; and all around it 

 the tubercles radiate, becoming large and having definite scro- 

 bicular circles and flat scrobicules until the edge of the space is 

 reached. This ornamentation is restricted to parts of the second 

 posterior intcrradial peristomial plates, and partly to the third on 

 either side, they being crossed by the fasciole. The first plate is 

 faintly marked with transverse ridges and distant miliaries. 



The ambulacral plates on, either side of these plates are narrow ; 

 and their ornamentation is composed of distant miliaries. 



Finally, the shagreen appearance of the whole test, caused by the 

 minute granular tuberculation,'is remarkable. 



The localities whence Lovenia Forbesi and the varieties Wooclsi 

 and minor have been obtained are numerous. Thus the Murray 

 cliffs have yielded the first two forms, Mount Gambier and the 

 Hamilton Tertiaries and the Mordialloc sections No. 1, 2, 3, and 4 

 the same, the last yielding also the var. minor. 



Genus Schizaster, Agassiz. 



A large specimen, partly in the form of a cast, but with the details 

 very well preserved, came from the " Adelaide district." It belongs 

 to this genus ; and from its resemblance to Schizaster ventricosus I 

 am disposed to give it that specific name. 



Schizaster ventricosus, Gray, Cat. of Echinida, p. 60. 



Dr. Gray obtained his specimen from Australia ; but the species 

 is more common to the north and east, in Siam, the Philippines, and 

 the Pijis. 



Genus Megalaster, gen. nov. 



The test is elliptical in outline, deeply incurved anteriorly and 

 slightly truncate posteriorly. It is long, broad, but depressed ; very 

 flat inferiorly, and sloping sharply from the ambitus upwards. 

 The apical system is in advance of the centre, and the test slopes 

 on all sides from it; it is small in relation to the dimensions of the 

 test, and there appear to be four small generative pores. The am- 

 bulacra are closed, petaloid, deep, and small for the size of the test. 

 The anterior ambulacrum is aborted, and the anterior groove is 

 broad and very deep at the ambitus. The other ambulacral petals, 

 which are closed externally, are very deep and slightly flexuous, 

 and the anterior pair diverge more than the posterior. The peri- 

 proct is large, elliptical, transverse, and situated above the margin 

 in a small truncation. The mouth is large, transverse, and placed 



