PEDICELLARLE OF ECHINODERMATA. 183 
bases are surrounded by tufts of spinules (pedicellariz). In 
very young specimens the pincer-like spicules are frequently 
wanting.” (‘ British Echinodermata,’ p. 84.) 
These pedicellariz are sessile in some cases or peduncu- 
lated in others, but the genus Uraster is distinguished by the 
pedicellariz invariably having two blades, sessile in the 
greater number of instances; and of two characters, either 
solitary or aggregated. 
The solitary sessile pedicellariz are found generally dis- 
seminated over the dorsal aspect of the rays and disc, 
situated in the areole of the skeleton, and attached to the 
roargin of the fenestree. This form of pedicellarize may be 
denominated valvate, or the sheep-shearing-shaped forceps, 
from its similarity to the shears, and from this circumstance 
the author has named them “ forficiformes.” They are 
very numerous on every animal of the genus Uraster, and 
are more readily discerned in dry specimens. 
This genus also possesses two kinds of aggregated pedi- 
cellarize—one valvate, the other pincer-shaped. 
The spines bordering the ambulacral groves are frequently 
seen covered with a flock of these pedicellariz, which have 
the same valvate or forficiform appearance as the solitary form 
previously noticed, but the blades of the shears are generally 
longer and more acute—in fact, more ‘‘mandibulate” in 
form. 
Both these valvate forms agree in having a basal portion 
and two blades; each blade is pointed and gouge-like, with 
transparent cutting edges running nearly three quarters of 
their length, and appearing with higher powers finely den- 
tated. The basal portion seen from above consists of two 
adherent cup-like cavities, somewhat quadrilateral in form— 
an oblong parallelogram, the angles of which are rounded. 
The margins of these cup-like cavities serve for the articula- 
tion of the broader ends of the blades, and when opened the 
whole organ presents the shears-like form described. 
The second form of aggregated pedicellarize wholly differs 
from the former, and consists of only two, having no basal 
portion. These are truly forceps-like in form, each blade 
crossing the other by a joint, not unlike the hinge of a pair 
of scissors or pincers, and having a dentated jaw-like margin, 
putting one in mind of a dog’s-tooth forceps, hence called 
‘<forcepiformes.” They occur around the bases of the dorsal 
spines in dense clusters, of some hundred or more to each 
spine, in glacialis, but are far less numerous in rudens. 
The fleshy base of this mass of pedicellarize occasion that 
icy look of the spine whence the specific name glacialis. 
