Hexactinellidae and Lithistida?. 459 



me ; and being exactly like Mr. Kent's, there was no difficulty 

 in recognizing its specific nature ; but on boiling a portion of 

 it in liquor potassoz, it was also found to possess the charac- 

 teristic scopuline shaft (PI. XV. fig. 1) together with a rosette 

 (fig. 11, d), both in great abundance in the mud with which 

 the tubular branches of the sponge were still filled, especially 

 towards their free closed extremities. It was then observed 

 in the mounted specimen that there were also a few rosettes 

 with elongated shaft-like axes, on which {he rays were some- 

 times capitate and sometimes pointed, the latter bearing a 

 strong resemblance to the spined shafts peculiar to Aphro- 

 callistes heatrix (PI. XIII. figs. 17 & 18). The presence of the 

 rosette in these two forms being new to me, I turned to the 

 examination of the type specimen of Aphrocallistes Bocagei in 

 the British Museum, described and figured by Dr. Wright {I.e.), 

 and found that it also contained the same kind of rosettes. 

 Lastly, I examined Aphrocallistes heatrix in the British 

 Museum, described and figured by Dr. Gray (I. c), and found 

 that, although this did not contain the globular rosette with 

 short axis so abundant in A. Bocagei, it contained that form 

 with elongated shaft-like axis in which the rays are occa- 

 sionally capitate (PI. XIII. fig. 19), thus so far retaining 

 this character of Aphrocallistes Bocagei. Hence, again, the 

 necessity of studying minutely all the spicules of these 

 sponges, which led me to write the descriptions of them above 

 given. It will now be observed that, in order to arrive at an 

 accurate knowledge of the Spongiadge structurally, they must 

 be studied elementarily in this way, and upon the amount 

 of this knowledge will depend the accuracy of our classification. 



I next took some minute portions from the fragment which 

 Mr. Kent sent me of his Farrea occa, and also from Mr. Gassiot's 

 before mentioned, but was not correspondingly fortunate here. 

 However, on returning to the deep-sea specimen dredged up 

 on board H.M.S. ' Porcupine ' (No. 3 a), which had grown on 

 a Lophohelia and had subsequently been enveloped in a Gum- 

 mina (Corticium abyssi), I found in one fragment, as the 

 illustration will show (PI. XVI. fig. 5), a spicule of the form 

 no. 2 (PI. XV. fig. 8) previously described under Aphrocallistes 

 Bocagei. This spicnle, as I have before stated, is not confined 

 to A. Bocagei, hut is found in Aulodictyon Woodwardii, Hyalo- 

 nema, and all the sarcospiculous Hexactinellidse possessing the 

 " birotulate spicule." Possibly it might be considered an acci- 

 dental instance, and therefore might not originally have 

 belonged to Farrea occa ; but in three or four instances it 

 was found thus imbedded. 



In each of two other fragments from this specimen of 



