1889.] NATURAL SCIENCES OF PHILADELPHIA. 71 



the oyster favors the invasion of its boring enemy. The free moving 

 clam, while alive, appears to be exempt from its attack, but the 

 shells of the dead clam are as thoroughly invaded and riddled as 

 those of the oyster. I have occasionally met with an isolated valve 

 of the Mactra solidissima, Pecten irradians, and the horse-mussel, 

 Modiola plicatula, which exhibited the perforations of the boring- 

 sponge, but none containing the living sponge. In one instance I 

 obtained a clam shell having attached to it a shell of Ilyanassa 

 obsoleta and tubes of Serpida, all together, drilled by the living 

 Cliona. On the cultivated oyster beds the massive Cliona is less 

 frequent than upon accumulations of dead oyster and clam shells 

 elsewhere, probably from the circumstance that it is more liable 

 to disturbance in its growth in collecting oysters from the beds. 



A boring-sponge closely resembling, if it is not identical with ours, 

 and having the same habits, occurs in European seas. It was first 

 definitely noticed by Dr. R. E. Grant, in the Edinburgh New Philo- 

 sophical Journal, 1826, p. 78, and found on the shells of dead and 

 living oysters (Ostrea edulis), in the Frith of Forth, Scotland. 

 The description of the sponge accords with my observations on the 

 boring-sponge as above indicated. From the accidental attachment 

 of some polyps to the sponge, observed by Dr. Grant, supposing the 

 polyps to belong to the sponge, he described it as a zoophyte and 

 named it Cliona celata. He also regarded the borings occupied by 

 it as not due to the sponge, but to annelids, though in the concluding 

 part of his account he remarks that it may be questioned whether 

 the shape of the silicious spicules and constant currents of the 

 papillse do not exert an influence in forming or enlarging the habit- 

 ation of the zoophyte. 



In 1840, Dr. G. D. Nardo, announced the occurrence of the bor- 

 ing-sponge of the oyster in the Adriatic, and gave to it the name of 

 Vioa (Un nuovo genere di Spongoli silicei.) Shortly after, Duver- 

 noy noticed the boring-sponge in the Ostrea hippopus, at Dieppe, and 

 gave to it the name ofSpongia terebrans (Comptes rendus, 1841, 683). 

 Dr. George Johnston, in 1842, in his History of British Sponges, 

 p. 125, described the boring-sponge of the oyster, under the name of 

 HaliehondHa celata, from the oyster beds of Inchkeith and from 

 the Frith of Forth. He also referred to the same species a massive 

 variety dredged in Butribuy Bay. 



In 1849, Mr. Albany Hancock, in a paper "On the excavating 

 Power of certain Sponges belonging to the genus Cliona" described 



