84 



THE FOSSIL ECHINOIDEA 



part of the antero-lateral ambulacrum, which is marked with the peripetalous fascicle, 

 and -passes backwards and downwards to reach the lower part of the truncation close 

 to the margin of the test, which it crosses with a downward curve. 



There are many specimens of this lAnthia in the collection from the Eanikot. 

 series : some have been slightly crushed ; others (which are younger) have not. There 

 appear to be two forms — that which has just been described, and a smaller. These 

 last have a more globose and less depressed appearance ; but in all the other points 

 they correspond with the first. 



Length of tlie type specimens. 

 inch. 



20 



i9 

 2 



20 



1-1- 

 -■■20 



14 

 20 



Breadth. 

 \l inch. 



i9. 

 20 " 



1 1 



20 " 



14 

 20 



Height, 

 inch. 



14 

 20 

 13 

 20 



20 



XX 

 20 



12. 

 20 



Length of specimen of variety. 



1 s _• 1. 



not quite \^ 



if inch. 



14 

 20 



Breadth. 



iff inch. 



Height. 



iB inch. 



12. 



2 55 



Locality. North-east of Band Vero, Eanikot series. Survey-number G H^. 



Illustrations of the Sj^ecies in Plate XX. 



Fig. 1. Actinal view. 



2. Side view. 



3. Apical system : magnified. 



4. Side view of variety. 



5. Fig. 1 from above. 



6. Posterior view. 



7. Young form: side view. 



8. Posterior view. 



Memarks. We were at first disposed to refer this form to the Linthia Arizensis, 

 d'Archiac, sp. ; but a careful study of the specimens contained in the collection has 

 convinced us that the differences are greater than would justify us in maintaining such 

 a conclusion. The outline of the test is broader, more angular, and with prominent 

 gibbosities ; the posterior height is much greater, the anterior slope is more rapid, the 

 posterior sloping truncation is concavely impressed ; the ambulacra are in much deeper 

 grooves ; the anterior petals are wider and more rounded at their distal extremities, and 

 the posterior pair are directed more backward and consequently at a smaller angle of 

 separation ; on the actinal surface the plastron is broad and well tuberculated, and the 



