CORBITELLA AND HETEROTELLA. 29 



in glycerine and under a high power of the microscope, I could 

 indeed trace the filament for some distance from the central node 

 into the rays, though nowhere with as much distinctness as in a 

 larger spicule, and soon it always became quite indistinguishable, 

 probably on account of the fineness of the rays themselves. So 

 that, no use could be made of the observation in clearing up 

 the question. 



The hexaster present in the species is only of two kinds : 

 viz., the floricome and the graphiocome. Notwithstanding a 

 thorough search made in my preparations, I have failed to dis- 

 cover a third hexaster form. Whether this negative character is 

 due to a loss by the species or is to be regarded as primary, is 

 of course difficult to say. Possibly the absence is to a certain 

 degree compensated by the presence of the interesting spiny 

 microhexactin above described. 



The floricome in Specimen A was mostly represented by 

 fragments ; only in two cases was it found nearly intact, measur- 

 ing in diameter 94 <>■ and 100 ,« respectively. In Specimen B 

 several coidd be measured, ranging 82-92,« in diameter. The 

 floricome is of a delicate appearance ; principals slender ; terminal 

 claws of moderate strength. 



The graphiocome as such was never found ; but the occurrence 

 here and there of unmistakeable rhaphides sufficiently attests its 

 presence in the species. 



In conclusion, a few words about the Euplectellid subfamily 

 to which the forms treated of in this Contribution belong, to be 

 followed by summarized statements of the characters of these. 



