281 



anterior pair. The interstitial ridges between the conjoined pores 

 of the paired ambulacra are minutely granulated. 



The test is minutely granular, and thickly studded with minute 

 tubercles, which become conspicuous on the anterior interam- 

 bulacra, more especially on the keels of the anterior groove. 



Dimensions. — Longitudinal diameter, 82 ; transverse diameter 

 at 30 mm. from the front, 87 ; height, 35 mm. ; width of groove 

 at ambitus, 11 ; in a medial position, 16 mm. 



Locality. — Glauconitic limestone, Aldinga Cliffs (one ex.). 



The conic abactinal surface distinguishes C. latecordatus from 

 other depressed species of the genus, whilst its broadly cordate 

 outline and large anterior groove are equally prominent charac- 

 ters. 



Sehizaster abductus, -^ptc. nov. 



Synonyms. — 1 Sehizaster ventricosus, Duncan, Q. J. G. S., 1877j 

 p. 61 ; id, 1887 (?ion Gray). ">, Sehizaster exoletus, Hutton, Cat. 

 Tert. Echinod., New Zealand, 1873, p. 43. 



Somewhat like S. vent^'icosus, but is proportionately broader 

 and more depressed, has less-tumid sides, the posterior-median 

 keel is less pronounced, and the outline is not so angular 

 posteriorly. The dorsal slope rises regularly from before back- 

 wards, culminating in the posterior extremity of the projecting 

 post-median keel, whilst the subanal area is broad and concavely 

 depressed ; characters so strikingly different from S. ventricosus 

 as not to permit a confusion of the two species. The anterior 

 petals are in broader and shallower grooves, which are less-arched 

 at the apex, so that they are markedly divergent from the odd 

 ambulacrum ; whilst in S. ventricosus they are nearly parallel. 

 The posterior petals are also less divergent than in S. ventricosus^ 

 and the odd ambulacrum is in a narrower and shallower furrow, 

 which only slightly indents the ambitus. The vertex is, more- 

 over, less excentric. 



Comparative dimensions of the two species in millimetres : — 



Length. Breadth. Height. 



>S'. ve7itricosus ... 42 35 33 



S. ahcluctus ... 58 55 34 



Localities. — -In the Eocene calciferous sandstone of the River 

 Murray Cliffs, near Morgan (two perfect exs.) ; Moorabool River, 

 near Geelong (Mr. Sweet, a cast). 



Professor Duncan, op. cit., has determined "a large specimen 

 partly in the form of a cast from the Adelaide-district " to belong 

 to the living ^S'. ventricosus, but I am disposed to regard it 

 as the present species which is the only one of the genus as yet 

 found in the Australian Tertiary. Under these circumstances it 

 would be unsafe to admit Prof. Duncan's identification on such 

 imperfect material, and the name should be expunged from our 



