SPONGES. 277 



Owing to changes produced during the process of fossilization 

 the minute structure of the canal walls cannot be determined 

 satisfactorily. Where the walls are thinnest, traces of the spi- 

 cules are preserved. They appear to have been very minute, 

 and mainly three-rayed. Also a few extremely small uniaxial 

 spicules seem to belong here. 



In the form and general aspect of the sponge, Strotospongia 

 resembles species of Anthaspidella so closely, that the utter 

 disagreement in their respective internal structures (so far as it 

 has been determined) is very surprising. On the other hand, 

 we are again surprised to find that the internal structure of Stro- 

 tospongia corresponds very closely with that of the massive 

 sponges for which Mr. S. A. Miller proposed the genus Dystac- 

 tospongia. Both of these genera, we believe, belong to the CAL- 

 CISPONGLE, which they resemble more than any other group of 

 sponges. At any rate, none of the characters so far determined 

 present any serious objections to our view, but on the contrary 

 all seem to justify a provisional classification with the calcare- 

 ous sponges. 



STROTOSPONGIA MACULOSA U. & E. 



PI. VIII, fig. 1, la, Ib. Ic, Id, 



Sponge depressed funnel-shaped, expanding rapidly above the 

 sub-cylindrical stem, which is of unknown length. Upper sur- 

 face concave, with the margin acutely rounded. Near the centre 

 there is a deep cloacal cavity or osculum, while six others, of 

 smaller size, and less deep are situated at varying distances 

 from the central osculum. Around each there is a series of 

 thin-walled canals, arranged in a radiate manner, from 1 to 1.5 

 mm. wide. The radiating canals extend but a short distance 

 from the oscula when they bend downward and are lost in the 

 confused plexus which prevails throughout the interior of the 

 sponge. Beyond them the thin sponge substance forms a very 

 irregular network, with large angular meshes. 



The under surface exhibits the apertures of numerous canals, 

 0.7 to 1.2 mm. in width, which are arranged in subregular longi- 

 tudinal series on the expanded portion of the sponge. On the 



