AULOSACCUS SCHULZEI. 113 



axis are either quite obliterated or represented by vestiges in the 

 form of an external and an internal knob. The rays, as measured 

 from the spicular center, are 100-250 ii (on an average 130 jx) 

 long and Ih-^l it broad at l)ase. For the greater part of their 

 length they maintain a nearly uniform thickness. Their surface 

 is entirely rough, the roughness being most pronounced near the 

 outer conically pointed end. 



The meshes of the dermal latticework are tolerably regularly 

 quadrate, measuring on an average 140 ii in length of sides. 



The gastralia (PI. VIII., fig. 27 ; PI. IX., fig. 11) are rough 

 hexactins, rarely pentactins and still more rarely stauractins, of 

 much greater dimensions than the dermalia. The paratangentials 

 mostly measure 200-275 //. in length and 10-15 n in thickness 

 at base. The distal ray is nearly as long as, or somewhat shor- 

 ter than, the paratangential in the same spicule, while the prox- 

 imal ray is generally longer than the same and may be 385 // 

 in length. The rays taper perceptibly towards the conically 

 pointed end ; their entire surface is nearly uniformly rough. The 

 manner of arrangement of the gastralia over the hypogastral 

 beams in completing the endosomal skeleton has already been 

 referred to. 



Of the hexasters, the oxyhexaster (PI. IX., fig. 2-7) is of 

 frequent occurrence among the parenchymalia. As in Hyalascus 

 it is present in either hemihexactinose or hexactinose forms but 

 probably never in the completely hexasterous. Axial length or 

 diameter, 100-150 //. The terminals which look moderately 

 strong are about 3 ^ thick at base, and are obsoletely rough on 

 the surface. 



