STAUROCALYPTUS AFFINIS. 187 



to terminate -with rounded tips. Their leugth as measured from 

 the spicular center is 130-200//; on an average, 160/^; breadth 

 close to base, 11-15 fi. In the second specimen the length was 

 100-170 /i or on an average 130 /<; the breadth, 11-10 p.. — The 

 dermal paratangentials form a tolerably regularly (juadrate-meshed 

 dermal lacework (PI. XIII., fig. 10). 



The gastralia (PI. XIII. , fig. 4) are hexactins with similar 

 but often longer rays than those of the derraalia. Length of 

 rays, 140-240//.; in the smaller specimen, 140-175//. The free 

 proximal ray is not distinguished from the others by a greater 

 length. The gastralia are present in far too sparse a number to 

 form a continuous lacework by themselves (PI. XIII., fig. 11). 

 They are found in irregular distribution in the spaces between 

 the excurrent canalar apertures as wx41 as on the endosomal 

 reticular beams, where these are developed. 



The oxyhexasters (PL XIII., figs. 7 and 9 ; PI. XIV., figs. 16 

 and 17) measure 130-152// in diameter (in the second specimen, 

 115-160//). They are exceedingly numerous both in the choano- 

 some and the endosomal layer. While in the former the hexact- 

 inose and the hemihexactinose forms predominate, in the latter 

 region the normally developed form is by far the most abundant. 



The normal oxyhexasters, occurring in the endosome or in 

 its proximity (PI. XIII., fig. 9; PI. XIV,, fig. 16), show two or 

 sometimes three, generally smooth, nearly straight and widely 

 divergent terminals to an excessively short principal. The central 

 node is often spherically swollen, but not sharply dermarcated 

 from the principals. 



In the subdermal space, oxyhexasters are altogether sparse 

 and those that do occur there are as a rule again normally 



