REPORT ON THE HEXACTINELLIDA. 307 



generally long, sliarp-pointed, sometimes knob-headed ; spicules acerate, retentive, 

 verticillately spined, attenuated, rectangulated, liexradiate, and subfusiform cylindrical, 

 entirely spinous. Main tube closed by an irregular siliceous network, which is deeply 

 concave. Pores aud dermal system unknown." 



Among the differences between Aphrocallistes hocagei and Aphroccdlistes heatrix to 

 which Wright called attention, but which hardly seemed to him to have more than a 

 varietal significance, was the entire absence of the "porrecto multiradiate spicules" in 

 the case of AjjhrocaUistes hocagei, — a distinction all the more essential, as these spicules 

 were found to be quite constant in Aphrocallistes heatrix. As further points of 

 distinction, he noted that "the areas forming the skeleton in Aphrocallistes hocagei are 

 much more regularly hexagonal than those in Aphrocallistes heatrix. The spines on 

 the bosses are very much longer in the former than in the latter species ; in it, too, the 

 central cavity is larger. The reticulated network-like lid is much more radiate in its 

 composition than in AphrocaUlstes heatrix. The bosses on the rays of the body skeleton 

 are often knobbed." He also announced that Alexander Agassiz had recognised, from 

 the description placed before him, the agreement between these and one of the sponges 

 dredged by Count Pourtales to the south-east of Florida. This was soon afterwards 

 confirmed by Oscar Schmidt, who examined the sponges dredged by Pourtales, and 

 described them in his Grundziigen einer Spongien-fauna des Atlantischen Gebietes. 

 He discovered the transversely disposed plate, described by Wright as a "reticulated 

 network-like lid," of the wide exhalent opening of the main tube, not merely at the 

 extremity, but also at severttl places in the interior of the tube, forming transverse 

 septa. 



Special attention was directed by Oscar Schmidt to certain spicules, which were very 

 similar to the forms described by Wyville Thomson in Aphrocallistes heatrix. Each of 

 the latter was provided with, a straight shaft and four knobbed terminal teeth, while 

 the former exhibited only three such knobbed terminal teeth provided with fine prickles. 



In 1870 Saville Kent also found, in the sponge material obtained by him during the 

 " Noma" Expedition, ofi" the coasts of Spain aud Portugal, Ap>hrocallistes hocagei, Wright. 

 From his own examination he established its specific distinctness from Aphrocallistes 

 heatrix, and he added, as further diff'erential characters, that the whole skeleton is much 

 more slender, and is wanting in that echinate aspect of the bosses and shafts of the radii, 

 characteristic of Apihroccdlistes heatrix. The " porrecto-multiradiate" spicules, which seem 

 in fact to be characteristic and typical of the genus, are not wanting, as Professor Wright 

 imagined ; but there are none of the verticillate spined forms so abundant in 

 Aphrocallistes heatrix ; while, on the other hand, Aphrocallistes hocagei is at once 

 recognised by the presence of abundant hexradiate spicula, having one extremity of the 

 shaft profusely spinous, and accordingly bearing a close resemblance to those that occur 

 in Pheronema grayi. 



