202 ARTHUR DENDY. 



poculum^ in which the oxeote spicules are not collected into 

 tufts. 



Heteropia. 



This genus bears precisely the same relation to the genus 

 Grantessa as Ute does to Grantia, the skeleton being of 

 the ordinary ''inarticulate'^ Grantessa type^ but with the 

 addition of large longitudinally arranged oxea in the dermal 

 cortex. For further details I must refer the reader to Mr. 

 Carter'sdescription of Heteropia (Aphroceras) ramosa(15). 



Vosmaeropsis (fig. 19). 



All three species included in this genus (4) exhibit, like 

 Grantessa and Heteropia, a well-developed layer of sub- 

 dermal sagittal triradiates; but as the other parts of the 

 skeleton vary somewhat in the three cases, it will be advisable 

 to consider them separately. 



Vosmaeropsis macera, the anatomy of which is repre- 

 sented in fig. 19, shows least deviation from the ordinary 

 Grantessa type. There are, however, no quadriradiates in 

 the gastral cortex, but I do not consider this a very important 

 character. The oxeote spicules of the dermal cortex are also 

 very variable in their development, and may be almost, if not 

 quite, absent ; but this, again, is not an important character. 

 Otherwise, the skeleton agrees closely with that of an ordinary 

 Grantessa in which no distinct articulate tubar skeleton is 

 developed. 



In Vosmaeropsis depressa (4) the skeleton is modified, in 

 accordance with the massive form of the sponge and the 

 arrangement of the canal system. The bulk of the skeleton is 

 made up of fairly large, subregular, or slightly sagittal tri- 

 radiates, scattered without definite order throughout the thick- 

 ness of the sponge, many having one slightly longer ray 

 pointing towards the dermal surface. Beneath the dermal 

 surface, but apparently only on the upper surface of the 

 cushion-shaped sponge, is a distinct layer of subdermal 

 sagittal triradiates, with inwardly directed basal rays. The 



