PLATE CXLVI. 



ECHINUS Biforis : basi sulcis quinque lineisque flexuosis radiatis 

 decern exarata foraminibus oblongis ad anum 

 duobus. LesJce apud Klein EcJiinod, p. 169. 

 t. 21. A. B.-~Gmel. Linn. Stjst Nat. 1. 1. p. 6. 

 7i. 3188. 64. 



Scutella. BlFORA : obtuse trigona, depressa ; foraminibus duo- 

 bus oblongis, ad disci partem posticum : ano ab 

 ore remoto. Lamar cJc, t. 3. p. 10. n. 7« 



Among the innumerable bodies endowed with life and the 

 visible exercise of all the vital functions, there are perhaps few more 

 extraordinary in their exterior aspect, or their internal organization, 

 than the tribe of animated beings of which the Placenta formed 

 Echini constitute a family ; they appear to be scarcely more than 

 a thin plate or lamina, the depression or flatness being in many 

 species so very considerable that unless broken they could hardly be 

 supposed to consist of an upper and lower crust, with an intervening 

 space in which the vital parts of the animal could be lodged. Many 

 of the Linnoean families of the Echinus genus occur with numerous 

 moveable spines or processes, appendices with which the animal is 

 enabled to move with more or less facility from one place to another, 

 those spines answering the purposes of feet : such are all the rounded 

 or rotundate kinds ; but in the Placenta-formed Echini the spines 

 are very small, being little more than asperities or pustules just 

 obvious to the touch, and which cannot therefore be supposed to 

 constitute members of equal use in facilitating its movements like 



