34 
Spatangites bicordatus, Tab. xlvii. Fig. 6, Lesk. In this fossil, 
which is but rarely met with, there exist, connected by a linear cari- 
nated ridge, two vertices, in which the ambulacra terminate. Both 
ends, thus becoming sulcated, the echinite is said to be bicordated. 
Spatangites carinatus, Tab. li. Fig. 2, 3, Lesk. This Spatangite, 
like the former, has a linear carinated ridge, connecting two vertices ; 
but, unlike the former, the narrow anal termination is not sulcated. 
It is also figured by Baier, Oryct. Noric. Tab. in. Fig. 43. 
The third family of this genus is considered by Leske as composed 
of those echini which form the genus Brissus *, of Klein : the chief 
characters of which are — the back not grooved, but striated ; four 
deep crenated and perforated sulci, as ambulacra ; the base tumid ; 
the anus and mouth patulous, and the latter bilabiated. None of the 
varieties of Spatangus brissus, into which, according to Leske, they 
all resolve, appear to be known in a mineralized state. 
The genus brissoides, of Klein, is adopted by Leske as the fourth 
family of Spatangi. The shells of this family, like the brissi, are 
ovate, and the back striated, but not lacunated ; the rays are flat. 
Spatangus brissoides, Tab. xxvn. b. Klein, is ovate, oblong, sub- 
cordated ; with four petaloidal, lanceolated ambulacra, with two rows 
of pores, connected by transverse striae ; large tubercles existing be- 
tween the ambulacra ; the rest of the surface being covered by gra- 
nulated risings. The mouth subrotund and reniform, surrounded by 
pores disposed in the form of a pentagonal star ; the middle of the 
base raised and tuberculated. 
Spatangus ovatus, Tab. xlix. Fig. 12, 13, Lesk. differs from the 
former, chiefly in being more convex; but this species does not 
appear to be known fossil. 
* Brissus. This word, is applied by Aristotle, and after him by Athenaeus, to 
certain genera of echini. The name Brittus is also elsewhere applied to them. Afyvr os 
is the designation, then, of a genus of echini, corrupted from zfyuroi, i. e. non commesu apti. 
