100 
BATHYDORUS LAEVIS SPINOSISSIMUS. 
found besides the ordinary ones also, however, a few 220-320 n in diameter. 
Their rays do not lie in one plane but form the edges of low obtuse pyramids 
with quadratic bases. In consequence of this and the fact that the rays are, 
in the same spicule, nearly equally long, the ray-length is a little more than half 
the diameter of the spicule. The basal thickness of the rays is in the regular 
stauractines 80-215 ju; the diameter is 4.5-9, generally 5-7 n- The rays of the 
giant stauractines 220-320 n in diameter, above referred to, are 6-15 /x thick at 
the base. The rays are generally terminally rounded and either cylindrical, at 
the end as thick as at the base; or, more frequently, cylindroconic, at the end 
only one to two thirds as thick as at the base; very rarely the ends are pointed. 
In respect to the degree of attenuation towards the end the rays of the same 
spicule are often unequal. 
The whole of the spicule is densely and uniformly covered with sharp conic 
spines, its central part being quite as spiny as the distal parts of its rays. The 
proximal spines are nearly vertical, the distal ones directed more or less obliquely 
outward. Large and smaller spines are irregularly intermingled; the largest 
are sometimes 4 n long. 
Stauractines with one or more rays reduced in length (Plate 15 , figs. 5, 9, 10, 
18, 21, 22) are quite frequently met with. Apart from the ray-reduction these 
spicules resemble the regular stauractines above described. When two of their 
rays are reduced, these reduced rays may be either adjacent (Plate 15, fig. 21) 
or opposite (Plate 15 , fig. 5). A stauractine in which all the four rays are 
reduced is represented (Plate 15, figs. 9, 10). This spicule is only 30 n in diame- 
ter, and has cylindrical, terminally rounded rays 8 m thick. 
Irregular stauractines with unequal interactine angles (Plate 16 , fig. 12) or 
with curved rays (Plate 15 , fig. 11) are met with much more rarely. Apart 
from the irregularities characteristic of them, they also resemble the regular 
stauractines above described. 
Among the dermal spicules with less than four rays, which are doubtlessly 
to be considered as stauractine-derivates with reduced ray-number, triactine and 
diactine forms occur. Most of the triactine stauractine-derivates (Plate 15 , 
figs. 4, 6) are straight or curved rhabds, 83-125 n long, from the central part of 
which arises a ray-rudiment 9-12 n long. Some of them, however, appear as 
more or less regular triactines with rays nearly equally long, enclosing fairly 
equal angles with their neighbours. The diactine stauractine-derivates are 
straight, or slightly curved, or strongly angularly bent. The latter resemble 
more or less widely open compasses. In regard to the thickness of their rays 
