190 
HYALONEMA (HYALONEMA) AGASSIZ1. 
Fig. 5. — Form A. Amphidiscs. 
near its centre to 8-20 n, and gradually at both ends to 8-15 n. From the 
central thickening arises a regular, or irregular, verticil of conic truncate spines 
which is 2-8 m long, and 2-5 n thick at the base. The ends (terminal faces) of 
these spines bear clusters of small secondary spinelets. The other parts of the 
shaft usually bear a few, rarely a good many, very low protuberances covered 
with clusters of secondary spinelets. These protuberances are circular in outline 
and agree in breadth and secondary spinulation with the spines on the central 
thickening. The shaft is traversed by a fine axial thread which, where it passes 
through the central thickening, is slightly thickened to a small but well-defined 
point. Traces of branch-rays of the axial thread (an axial cross) could be 
detected neither here nor elsewhere. The terminal anchors are composed of 
eight to twelve recurved teeth. They are 40-80 n in length, that is about a third, 
generally a little less than a third, of the whole spicule, and 41-86 /x broad. The 
proportion of the length to the breadth of the anchors is 100 to 91-120, on an 
