324 
REPORT ON ZOOLOGY, MDCCCXLII : 
the dorsum, stand in connection with ambulacra. The opening of the 
mouth lies opposite the small apicial rosette, which is composed of three 
different parts, namely, the madrepore-form plate, the plates containing 
the sexual openings, and those which bear the ocelli. These different 
plates are also so intimately connected to each other, that they can with 
difficulty be separated. The spines vary in form according to the genera 
and species ; those of the upper surface are mostly clavate, those of the 
under straight and pointed ; several species of Mellita and Encope have 
a third sort of spines, which are flattened laterally at the ends. These 
spines, which are organized, as in Echinus, can be moved by the living 
animal on all sides. The greater number of the Scutellce are grey or 
violet coloured. In those in which the margin of the shield is entire, the 
anus appears farther from the mouth than in those the margin of which 
is incised. The cavity in the interior of the shield is divided by many 
perpendicular partitions. The organs of mastication of the Scutellce are 
constructed much on the plan of the teeth of Echinus. The intestinal 
canal, which winds through the cavity of the body, contains, generally, 
fragments of small corals and shell-fish, 
Agassiz divides the Scutellce into thirteen genera, which are all 
figured. The four genera, Runa, Amphiope, Scutella, and Scutel- 
Una, containing only antediluvian forms, are here omitted. Of the 
genus Rotula, two species are described : R. Rumphii {Scut, dentata, 
Lam.) and Augusti {Scut, octodactyla, Lam.) To the three already 
known species, Mellita quinquefora, Ag., Lam., testudinata, Kl., 
hexapora, Ag., L., Gm., Agassiz has added two new species: M. 
similis, disco suborbiculari vel subquinquangulari, lunulis sex, basi un- 
dulata, sulcis ambulacralibus valde ramosis ; and M. lohata, disco sub- 
orbiculari, lunulis sex, lunulis ambulacralibus posticis apertis, petalis 
brevibus, ovatis, subclausis, poris genitalibus ocellaribusque vere distinc- 
tis. The genus Encope is represented by eleven species, of which nine 
are new, viz., — E. {Scutella) emarginata, Ag., Lam. ; tetrapora, Ag., 
Blainv. ; micropora, perspectiva, cyclopora, ohlonga, suhclausa, Valen- 
ciennesii, Michelini, grandis, and StoJcesii, Ag. To the genus Loho~ 
phora, four species are reckoned : L. {Scutella) hifora, Ag., Lam. ; 
truncata, Ag. {Scutella hifora, var. 2, Lam.) ; hijissa, Ag., Lam. ; aurita, 
Ag., Blainv. {Scutella hijissa, var. 2, Lam.) Besides Amphiope hiocu- 
lata, Ag. {Scutella hifora, var. 3, Lam.), Agassiz describes a second 
species : A. perspicillata ; disco valde depresso, postice subrostrato, 
lunulis subcircularibus, petalis subovatis, acutis. — Of Echinarachnius 
there are three species described, E. parma, Gray, Rumphii, Ag., 
Blainv., and atlanticus. Gray ; and of Arachnoides only one, A. pla- 
centa, Ag., Lam. The genus Laganum has twelve species, of which 
nine are described for the first time : Laganum, Bonani, Ag., Kl., 
{Clypeaster laganum, Lam.) ; depressum, decagonum, Lesson and Ag, ; 
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