LINOPNEUSTES LONGISPmUS. G3 
comparatively smaller, and covered by smaller plates than in that species, 
and is transversely elliptical. The apical system in both the species of 
Linopneustes is more compact than in Paleopneustes. 
The odd antei'ior ambulacrum of L. lonjispinus is more sunken at the ambi- 
tus than in the Japanese species. The lateral ambulacra are more petaloid 
than in any other species of either Linopneustes or Paleopneustes thus far 
known ; in some specimens they end at the extremity much as they do in 
Eupatagus. (PI. XX. Fig. 1.) The petaloid pores of the two rows are of 
nearly the same size, placed close together on the outer edge of the ambula- 
cral plates. The petals extend somewhat more than half-way from the 
apex to the ambitus. TIfe secondary tubercles are small, of uniform size, 
and the whole surface of the test is uniformly covered by minute miliaries. 
The primary spines of the abactinal surface are long, slender, curved, (PI. 
XIX. Pig. 1, PI. XX. Fig. 1,) some of them measuring nearly a quarter of 
the test in length. The thin slender and straight secondary spines are not 
more than 3 or 4 mm. long ; the thin hair-like miliaiy spines are nearly as 
long, and are generally curved. 
On the actinal side of the test the primary tuberculation is close in the 
posterior lateral interambulacral areas on one or two plates near the ambitus, 
but towards the actinostome the primary tubercles increase in size (PI. XX. 
Fig. 5), and at the same time become less numerous. The tuberculation of 
the actinal plastron is smallest along the median line, the tubercles increas- 
ing in size towards the outer lateral edge adjoining the broad bare posterior 
interambulacral areas. The spines of the actinal surface are shorter and 
more slender than those of the abactinal surface ; they are curved, and those 
adjoining the bare posterior ambulacral zones are more spathiform than the 
spines on the rest of the actinal surface. The actinostome of this species 
is comparatively smaller (PI. XX. Fig. 6) than that of L. Murratji, meas- 
uring only 10 mm. in longitudinal diameter in a large specimen of 105 
mm., while in one of L. Murrani of 85 mm. the actinostome measures 
nearly 15 mm. 
When alive, the test is pinkish or flesh-colored, the large primary 
spines of the abactinal surface having a yellowish tint with a whitish 
silvery lustre. 
