20 DlCTYOSPONGID^ 



18 good reason to believe that the quadrilles made l)y the large primary 

 fascicles ai-e not subdivided by similar bundles of less size, although an 

 extremely fine reticulatitm of these areas may be seen, which may be due 

 to regularly juxtaposed stauractins not on the inner wall, but over the outer 

 surface of the sponge. 



In the great saucer-shaped fronds termed Hypiiant^nia (male 

 Uphant^nia), the broad radial and concentric bands form quadrate areoles 

 which may have been largely or wholly free of sj)icular structures of any 

 kind. The sandstone matrix in which the few known specimens of this 

 sjx)nge have been found is not favorable for the i-etention of tenuous spicules, 

 though a similar rock shows at times, the continuity of very fine skeletal 

 films in some other of these sponges. But had' there been, over these open 

 quadrules, a coating of fine, isolated dermal spicules, their disappearance 

 rather than their retention would be a reasonable expectation. A single one 

 of the five specimens of Hyphant^nia at present known, shows traces of such 

 a film at the angles of the great quadrules. 



by liim, warrants tbe application of the term SpHiERODiCTYA to the interesting generic type of strnctare 

 here analyzed. 



*Tbe original specimen of Cyathophycus subaphcericu) is preserved in the Miisetim of Comparative 

 Zoology at Cambridge. Lilte the speoimons described by RaukI'' it shows no evidence ot reticulation or 

 siiicnlar strncture, nor are there any traces of peripheral spicules. The central area, supposed to be the 

 oscnlum, is irregnlar and there are no means of determining whether it is actually such or is only a casual 

 feature.* Upon application to the curator of the United States National Museum at Washington, for 

 antbentic specimens of Teganium tubsphwricum for comparison with tbe material above described, wo have 

 been kindly allowed to examine a portion of the material studied by Dr. Raukf and identified by Mr. 

 Walcott as his species. Of the specimens received, one is a minute cup-sbaped budy similar in form to 

 those described by Raufp and with a similarly obscure skeleton ; three others are cups of like form but 

 larger size and with a quadrate network already defined ; these resemble young individuals ot Cyathodietya 

 re<ic«Ja/a and all the restare thesmall circular bodies witli pseudopodia like perijiherals-picules. A portion 

 of a single cluster of these is represented in figure 14, and the enlargement of one of the individuals (tig. 15) 

 shows the clearly defined spicular layer coexistent with the spiny outer wall, while in all the smaller examples 

 the spicules of the skeleton, except those of the outer wall, are not evident. As it was still difBcnlt to appre- 

 hend the evidence upon which the determinations made by Raui'F were based, Mr. Charles ScirucHKRT, 

 curator of invertebrate palaeontology in the National Museum, was requested to examine the specimens 

 whith bad been figured by that writer, with especial reference to the following points: (IJ, Whether 

 the specimens figured by Ra0fk iu his fig. 4, pi. iv, showed distinct evidence of possessing an aperture, or 

 whether the areas represented as apertures might be exfoli.atious of the thin pyritized films ; (2), whether 

 these three cups are all on the same block and are convex as represented ; (3), whether any of these small 

 specimens, when moistened, show a series of peripheral spinules; and (4), whether tbe larger specimen 

 represented in op. cil. fig. 3, has the unresolvable pyrite film and the great aperture, as represented. To 

 these inquiries Mr. SciiucHERT has, after careful inspection of the material, answered very explicitly: 

 ( 1 ), "There is no evidence of an aperture in any of the three small specimens studied by Raukk. Where these 

 arc indicated in the figures there has been a partial or complete removal of tbe ])yritizcd film in the speci- 

 men"; (2), " The three figures given by Rauff are taken from three separate and distinct specimens so 

 that fig. 4 is ideal. The apertures are drawn in as well as the convexity." (3), "No peripheral spicules 

 can be detected in these specimens." (4), "There is a thin pyritized film which has been varnished over, 

 aud in none do I distinguish spicules. The aperture in fig. 3 is also drawn in." 



*We have had no opportunity of examining this specimen, but the above statements are based upon an 

 czaminatiou kindly made by Prof. Ali>hf.us Hyatt. 



