| OCR Text |
Show 1905.] SPONGE CLATHRINA CONTORTA. 19 identity of contorta and spinosa, it is hardly necessary for me to express my opinion with regard to those systems of classification which define not only species but even genera of Ascons by the presence or absence of monaxon spicules. Before such a character as the presence or absence of monaxons can be used for systematic Text-fig. 6. Abnormal gigantic spicules of the class of the monaxons from a specimen of Clathrina contorta from Banyuls (Topsent 12 e). Magnified about 150 linear (i. e. half as much as the spicules figured in text-figg. 2-5). purposes, it is necessary to understand clearly what is meant by a monaxon spicule. In calcareous sponges a spicule of this class may be one of two perfectly distinct things. It may be, on the one hand, 2* |
