M. A. Pomel on the Classification of Echinida. — 227 
5. The Holasteria have the apex lengthened in conse- 
quence of the intercalation of the ocellar pieces between the 
genital pieces. The petals are still even with the test, with 
the pores but slightly developed in most of them. Some 
fascioles may be seen at the ambitus. In some the apex is 
continuous (Holaster) ; in others it is disjointed, and there are, 
as it were, two ambulacral summits (the sole genus is Meta- 
porinus). 
The Ananchytida are divided into two groups: the first, 
with the apex elongated, Offaster; the second, with the apex 
compact, Stenonia. 
The Lampadiformes are either edentate or furnished with 
teeth. The former are divided into the Kchinoneida, with a 
mouth without tubercle, er floscule, and with simple or sub- 
petaloid ambulacra; and Cassidulida, furnished with a flos- 
cule and tubercle at the mouth, and with petaloid ambulacra. 
The second are divided into the Clypeastroida, with petaloid 
ambulacra, and the Echinoconida, with simple ambulacra. 
The Echinoneida comprise three types :— 
1. The Dysasteria are still almost spatiform, and many 
authors have united them with the Ananchytida; but they 
have the ambulacra of the Lampadiformes on the inferior sur- 
face; their ambulacral summit is disjointed in the true Dys- 
aster, and simply elongated in Hyboclypus. 
2. The Echinonea have the ambulacra simple and uniform 
from the mouth to the apex, which is compact ; the peristome 
is often oblique ; of fossil genera Pyrina may be cited. 
3. The Caratomia also have their apex compact, but 
their ambulacra pass into the petaloid form ; they are almost 
simple in Caratomis, subpetaloid and unequal in Asterostoma, 
and petaloid in Pygaulus. 
The Cassidulida are those of authors, less the Caratomia. 
Some have a very rudimentary floscule between the cushions, 
and the petals are dissimilar in Archiaria, similar in Clypeus ; 
others have a well-developed floscule, with conjugated pores 
in Pygurus, non-conjugated pores in Hehinanthus; and a 
fifth phyllodean type is remarkable on account of the short- 
ness of the petals, Maujasia, foreshadowing the following 
type. 
The Clypeastroida remain, divided into Clypeastres, Scutellae, 
and Lagane. However, it would be perhaps convenient to 
divide the last-mentioned group into true Lagane, with a 
buccal rosette and petaloid ambulacra, and Lehinocyami with- 
out buccal rosette, and with ambulacra hardly petaloid, and 
formed of non-conjugate pores. 
The Echinoconida are, again, those of authors, less the tooth- 
