190 



HYALONEMA (HYALONEMA) AGASSIZI. 



Micramphidiscs 



Macramphidiscs 





c o 



CTl O 



i O ^ 



I CO CO 



O •* to 



Tf .-H M 



i>; .-^ in 



OO Tf 'a' 



I I I I I I I I I I I 

 ootO'^tDa>oooc^jcN)ai<r3^i'mc^tD 



t>;t^(NMoqi-HCMOt^CO"-IOCMOOO 



cri'S-oidcviooot^uDo^aioitxi.-Ia^ 



rtlO^OC^QOOOa^O»-HC^-rtLOt^OO 



O <M 



00 



r-l (b 



in r^ 



<>4 M 



a> on 



O CO 



M I I I I I I I I I I I I I I I I I I M I I M M I M I I I 



►J -1 



IM CD 

 ■^ 00 



in o> 



CO 

 rt CVJ 

 i-J CO 

 CM CSl ' 



O O -* 



p -^ 1-; 



Tt t^ T-H 



CO CO ■^ 



(OOOt£>-^tOCriOOOCMCMCT>CO'5tLnt^ 



CMt>;i>^c^CMoq'-Hcgp^--cOf-;ocMoq 

 Lriai-^cD*ocNiooQt^ot-^c^cM'tdT-H 

 -^•■^iniotoooooooorHCM-^Lnt^ 



00 o 



—I CM 



00 r-i 



CM in 



CM CM 



I— t <Ti 

 00 ■* 



t> o 



CN CO 



Fig. 5. — • Form A. Amphidiscs. 



near its centre to 8-20 n, and gradually at both ends to 8-15 yu- From the 

 central thickening arises a regular, or irregular, verticil of conic truncate spines 

 which is 2-8 ju 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 ^ in length, that is about a third, 

 generally a little less than a third, of the whole spicule, and 41-86 ju broad. The 

 proportion of the length to the breadth of the anchors is 100 to 91-120, on an 



