from the Antarctic 8ea, 415 



Ohs. All that I have to offer respecting this sponge is the 

 description of these two forms of spicules. It might seem 

 strange that I should endeavom- to establish a new genus upon 

 them, were it not considered that the yowr-armed anchor-head 

 (fig. 7) is unique, so far as our acquaintance with the Spon- 

 giadie at present goes ; that is to say, with the exception of 

 Acarnus innominatuSj Grray, where there is a fourth arm, but 

 in a totally different kind of spicule (Annals, 1871, vol. vii. 

 p. 273, pi. 17), I know of no other instance. Secondly, the 

 four-armed, spreading, or great peripheral spicule (fig. 1) is 

 so far identical with that of Carteria and Holtenia^ but totally 

 differs from it in being spiniferous instead of smooth. Perliaps 

 the minute cruciform-headed and spined spicules congregated 

 in multitudes along the course of the smooth arms in Carteria 

 and Holtenia may be represented by the spines on those of Ros~ 

 sella. The only question, therefore, is, whether the two spi- 

 cules belong to the same sponge or to two different s])onges ; 

 and this seems to be answered by the facts that the two forms 

 are analogous to the anchor-head or anchoring spicule and the 

 great cruciform one of Holtenia respectively, and also that 

 both forms are equally and abundantly present about the 

 fragments of Tethija antarctica., wherein they have become 

 entangled, to the exclusion of every other kind, except those 

 which belong to the Tethya itself. Thus we may fairly as- 

 sume that they both belonged to some deep-sea sponge which, 

 thus differing from all others yet known, merits a separate 

 genus, with perhaps no more appropriate name than that of 

 " BosseUa^'' after the great navigator who dredged them up 

 from the bottom of the Antarctic Ocean. 



It is im]:)Ossible to say how long the shafts of the anchor- 

 headed spicules might have been, although the longest portion 

 that I have found is attenuated at the fractured end ; for, 

 although this generally indicates an approaching termination, 

 still the attenuation may or may not be much prolonged. 

 But, judging from the average of specimens found, I should 

 say, as before stated, that the shaft probably did not exceed 

 two inches.. 



The occurrence of a fifth arm in the direction of the shaft, 

 forming a kind of spike at the end (fig. 8), seems to be too 

 common to be abnormal, and therefore allies this sponge still 

 more to the Hexactinellidas of Schmidt. 



I also found one of these six-armed spicules in which there 

 is an extension of one of the recurved arms to such a degree 

 as to be almost equal in size and length to the shaft (fig. 9, a). 

 This, I fancy, must be an abnormal form. 



In no portions of Tethya antarctica that I mounted in Canada 



