29 
each two rows, uniting at the end of the grooves. Two of the am- 
bulacra, the shortest, are directed obliquely towards the narrow 
truncated extremity ; two others, longer, pass obliquely towards the 
broader end ; and the fifth passes straight to the mouth, forming the 
dorsal groove. Along the middle of the opposite part, a keeled edge 
passes directly to the anus. The vertex is perforated by four large 
pores. The mouth is reniform ; the upper lip triangular, and extended 
ovei the low ei . The anus is round, and placed in the upper margin 
o t e acute extremity. From the anus, a slight depression passes to 
ower margin ; at each of the angles of which is a protuberance, 
surrounded by a broad smooth surface. 
Specimens of this species are found in many parts of Europe, but 
particularly in Germany and in England. They are the most frequent 
fossds m the chalk-pits of Kent and Essex, and are frequently found 
filled with flint. These are the Echinites cordati vulgares of Lhwydd 
Lithoph. Fig. 964—96/. 
Two more varieties are noticed by Leske : the one, sulcis crispis, 
does not, in the figures referred to, appear to possess this particular 
character; and the other, norvagicum , Tab. xxm. e. f. Klein, varies 
irom the preceding, in being a little more oblong in its form. 
Spatangus lacunosus, Tab. xxm. a. b. Tab. xxiv. a. h. and Tab. 
xxvii. a. Klein. This fossil, which has indubitable claims as a 
istinct species, is of an oval form ; its upper surface gibbous, and its 
un ei rather convex. At the vertex are two, or, according to Muller, 
oui puncta. F rom the vertex immediately proceed four deeply sul- 
cated obtuse ambulacra, with angular margins : within the Grooves 
are four rows of pores, connected by transverse lines. The two 
posterior ambulacra, directed towards the narrower part of the shell 
are shortest, being sometimes merely two deepish fossulee : between 
the two anterior ambulacra is disposed another deep groove, which is 
also beset with strias and puncta. On each side of the shell, are 
several gradually rising prominences ; from which pass, in different 
