1S4 



ECHINIDtE. 



A Table showing the Classification or the ECHINID^. 



Family. 



Sections. 



Diagnosis. 



Genera. 



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Inter-ambulacra with irregular sculptured plates on the upper | 



surface of the test. J ^LYPTlcus, Agassiz. 



Upper surface of both areas finely plaited ; large tubercles at 

 the base only ; mouth small. 



Plates of both areas with pyriform depressions in a portion 

 of the line of the sutures ; ambulacra wide. 



Plates with deep depressions along the whole line of the 

 sutures ; ambulacra narrow ; mouth small. 



Numerous small, equal-sized tubercles in both areas ; two rows 

 in the ambulacra, and four to ten in the inter-ambulacra. 



Surface granular, with numerous small, close-set tubercles ; 

 mouth small ; peristome feebly indented. 



Inter-ambulacra lobed, with numerous small, close-set tuber- 

 cles ; mouth large ; peristome pentagonal. 



CoDioPsis, Agassiz. 

 V Temnechinus, Forbes. 

 Opechinus, Desor. 



EcHiNOCiBARis, BesmouUns. 

 > CoTTALDiA, Besor. 



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Magnotia, Michelin. 





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-Both areas naked in the middle, tubercles on the sides, with 

 sutural pores, and a tuberculous base. 



Tubercles numerous, equal-sized, sporadic ; inter-ambulacra "i 

 with naked horizontal spaces in the line of the sutures ; > 

 angular pores. J 



Mespilia, Besor. 

 MiCKOCYPHUS, Agassiz. 



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^Tubercles small, limited to the sides of the areas ; test globu- l 



lar, with a very small pentagonal mouth. | 



Tubercles small, numerous, equal-sized, in vertical and hori- l 



zontal rows ; larger at the base ; mouth large, pentagonal. | 

 Tubercles numerous, in many unequal, vertical rows ; mouth 



moderate ; peristome feebly notched. 

 Tubercles numerous, same size in both areas ; mouth small ; 



peristome with deep, narrow slits. 

 Tubercles unequal, two or more rows in each area, with seconda- 

 - ries ; mouth very large, pentagonal, with wide, deep notches. 



CoDECHiNUS, Besor. 

 PoLYCYPHUS, Agassis. 

 PsAMMECHiNUS, Agassiz. 



Echinus, Linnaus. 

 Stomkchinus, Besor. 











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^ Tubercles small, irregular, sporadic ; middle of the ambulacra 



naked ; pores at the angles of the plates. 

 Tubercles small, numerous ; the inner row of pores se- ] 



parated from the two outer rows by a line of tubercles. [ 



Tubercles not prominent ; the outer and inner rows of pores i 



rectilinear and regular, the middle row irregular. [ Tripneustes, Agassiz. 



Amblypneustes, Agassiz 

 BoLETiA, Besor. 



