CORBITELLA AND HETEROTELLA. 9 



terminations. They may be so short as to measure only 40/' in 

 length with a breadth of 10 y- ; but the size and the proportions 

 are subject to much variation, some of the spicules wellnigh 

 approaching the ordinary pentactin gastralia or the hexactin 

 parenehymalia in these respects. The general appearance of the 

 spicules strongly reminded me of the oscularia of certain Ewplec- 

 tella. Apparently the same kind of spicules was made known by 

 Marshall ('75, p. 212, PI. XVI, figs. 66e-h) from Corbitella 

 clegans and was held by him to be the oscularia. I doubt the 

 correctness of this interpretation. So fir as is known to me, the 

 occurrence of well differentiated oscularia is confined to the genus 

 Euplectella ; and moreover, I have found in Regadrella ohinoseana 

 spicules similar to the kind in question scattered among the 

 parenehymalia (Ij., '01 ; PI. VIII, figs. 27, 28, 34). 



The hexasters consist of the floricome, the discohexaster and 

 the graph iocome. 



The floricome was found in some numbers in more or less 

 fragmentary states. It measures 72-83 n in diameter. The princi- 

 pals are slender and bear each a perianth of 7 or S terminals of 

 the usual character. The claws, of which there are three or 

 four to each terminal plate, are very small. In many cases of 

 the rosette, only the basal parts of the terminal perianth re- 

 mained, the missing parts having been broken off. 



Comparatively large and strong-rayed discohexasters (PI., 

 figs. 10 and 11) occur in great abundance. Diameter 100-130 /', 

 occasionally reaching up to 145,« (on an average 120 /;). Each 

 exceedingly short or almost obsolete principal bears 2 or 3 

 diverging terminals, which, thickening somewhat towards the 

 outer end, finally terminate in a convex, marginally pronged, 

 conspicuous disc, about 16 f* in diameter as measured from tip to 



