56 
CAULOPHACUS SCHULZEI. 
then abruptly. Its distal part bears numerous fairly large spines, its proximal 
part fewer and smaller ones. Sometimes this part of the ray is nearly smooth. 
Exceptionally the proximal ray is reduced or hypertrophied. When reduced 
it is 7-40 /d long, more or less cylindrical, as thick throughout as the normal 
proximal ray at its base, and terminally rounded. A hypertrophic proximal 
ray observed (Plate 11, fig. 13) was 150 m long, considerably thickened in the 
middle, attenuated to a rather sharp point, and densely covered with large 
spines. It measured at the base 16 n and at its thickest point 25 m in transverse 
diameter. Another still more hypertrophic one in all respects resembled the 
(opposite) distal ray. 
The lateral rays are similar to the proximal ray, but more frequently smooth 
in their basal part. They are 80-157 n long, and 8-18 m thick at the base. 
The lateral rays of the same spicule are usually fairly equal. But in one 
quite abnormal pinule which I found in the large specimen D they were very 
unequal. In this remarkable spicule two adjacent lateral rays were hyper- 
trophic, covered with long spines, and similar to the distal ray of an ordinary 
pinule, whilst the other two laterals were normal and the spinulation of the 
distal ray so much reduced that it resembled the (normal) proximal ray. 
I measured a good many pinules of four different specimens (B, C, D, and E). 
The results of these measurements are tabulated on p. 57. Specimen E, which 
was taken for detailed study because it appeared to be a part of a specimen 
larger than any of the nearly complete ones, was too fragmentary to allow of 
a distinction between its dermal and gastral faces. The dermal and gastral 
pinules of this specimen are therefore not distinguished in the table. 
From this table the following conclusion concerning the differences in the 
dimensions of the pinules can be drawn. There is, in specimens of similar 
dimensions (B and C), a not inconsiderable variation in the dimensions of the 
pinules, particularly the length of the distal ray. In the large specimen D all 
the rays of the body-pinules attain a greater thickness and the proximal and 
lateral rays also a greater length than the corresponding rays of the correspond- 
ing pinules (dermal and gastral) of the small specimens B and C. The rays 
of the dermal pinules are thicker at the base than the corresponding rays of 
the gastral pinules of the same specimen. This applies also to the maximum 
thickness of the distal ray with its spines in specimens C and D, but not in B. 
The distal rays of the gastral pinules attain a considerably greater length than 
the corresponding rays of the dermal pinules of the same specimen. The other 
rays are in some specimens longer in the dermal, in others longer in the gastral 
