NUCLEOLITES. 557 



the actinal surface is regularly concave, arching towards the mouth from the 

 rounded edge ; the posterior part of the transversely elliptical mouth is on 

 a lower level than the anterior lip, — the first trace we have found of the 

 projecting lip, so highly developed in Spatangoids, a character used at one 

 time to distinguish the Cassiduloids from the Spatangoids proper. The con- 

 tinuation of the outer poriferous zones is quite distinct from the edge to the 

 actinostome, running gradually into the phyllodes, which are simply diverg- 

 ing lines of pores from the actinostome. The tuberculation of the interam- 

 bulacra at the actinostome is small, it consists of primary tubercles closely 

 crowded, but in all specimens examined no buccal bourrelet had been de- 

 veloped. 



The spines are still preserved on the specimen originally figured by Milne- 

 Edwards for the illustrated edition of Cuvier's Regne Animal. They are 

 short, stout, resembling in their general structure the spines of Echinolam- 

 pas, as we know them from those of Echinolampas depressa figured in Part 

 II. of this Revision, and of E. Hellei, of which alcoholic sj>ecimens are pre- 

 served in the Jardin des Plantes. 



The general coloration of dried specimens was yellowish-brown ; the test 

 somewhat darker where the tubercles are more closely set ; and the spines 

 mottled with dark and light brown, usually tipped with the lighter tint. 



New Zealand ; Madagascar. 



(ECHINOBRISSUS.) Nucleolites. 



Nucleolites La.mk., 1801, An. s. Vert, (par?.) 



I have retained provisionally the separation into two genera of Echinobris- 

 sus proposed by Desor and D'Orbigny, though, from the examination of the 

 scanty material of living species, the splitting into two sections of this genus 

 seems scarcely warranted ; the mere conjugation of the pores is an insufficient 

 character, as in specimens of N. epigonus and of E. recens we find in the same 

 individual a petal in which the conjugation is marked, another where it 

 is indistinct, and frequently the corresponding one in which the conjugation 

 cannot be traced. Limited as the genus Echinobrissus is here, I have taken 

 as type of the genus, Echinobrissus recens, and as the type of one sub- 

 genus of it, Nucleolites epigonus ; subsequent observations will, I have no 



