142 



2. F. vertice centrali. This differs from the preceding 

 only in the vertex being central. 



3. F. ervum. Globose ; the circumference inclining to 

 oval ; the base narrow ; sides sulcated ; and the ambulacra 

 somewhat raised. 



4. F. craniolaris. Anterior surface globose, the pos- 

 terior subangular, pulvinated, and abrupt ; the circumference 

 elliptical ; the vertex excentric ; the base rather narrow. 



The 5th, 6th, and 7th species of Phelsum, turcica, vicia, 

 and ovata, appear to be merely varieties of the fourth spe- 

 cies, craniolaris. The 8th and 9th species, latliyrus and 

 equinuS) do not appear to be marked by any characters de- 

 cidedly distinctive. 



10. F. angulosa. Appears to be distinguishable from the 

 circumference possessing somewhat of a quinquangular form. 



11. F. ovalis. This, besides being of an obtusely oval 

 form, is marked by four pores existing in the vertex. 



12. F. incequalis. Bearing the form of an apple pip, or 

 seed, ovate, very slightly pentagonal ; the back uneven and 

 anteriorly gibbous, posteriorly slanting and flattish ; base 

 subglobose and rather narrow ; sides sulcated ; petals sub- 

 pulvinated ; the apex central. 



13. F. cor ranee, and Sp. 14, F. paddehart. Appear to 

 be varieties of the 12th, F. incequalis. 



These small echini have been, it appears, found only recent 

 in the Adriatic, and on some parts of the American coast. 



14. F. ovulum. This is the least known of these echi- 

 nidae, being about the size of a pea ; globosely ovate ; the 

 base rather narrow ; ambulacra short, and separate at their 

 terminations. 



15. F. tarentina. Ovately elliptical; rather convex; 

 plano-convex beneath ; ambulacra short and disjoined. 



GENUS XI. Echinoneus. Obovate or suborbicular, rather 

 depressed, of a boat-like form ; the ambulacra, formed by 

 ten grooves, radiating from the vertex to the base. 



