1887.] 



NATURAL SCIENCES OF PHILADELPHIA. 



207 



surface of rotules dome-shaped ; rays ])rolouged, terminations acute ; 



malformations frequent, 

 spiued spicules. 



These are mixed with occasional linear 



Gemmule spicules abundant, 

 crossing each other upon the 

 crustless, chitinous body. 

 Their shape when smooth is 

 robust-fusiform, with pointed 

 terminations : the great ma- 

 jority, however, have from 

 one to six or more long spines, 

 non-symmetrieally placed, but 

 with an evident tendency 

 to group themselves at points 

 about one-fourth tlie length of 

 the spicule from one or both of its extremities. 



Meas. Diameter of gemmules 0.036 inches ; skeleton spicules 

 0.0068 by 0.0002 inches; length of average dermal birotulate, 

 0.00066 inches ; and of those of the gemmulse 0.00145 inches. 

 Hab. Encrusting stones in shallow water. 



Loc. Lakes or ponds in the vicinity of Heart's Content, New- 

 foundland ; collected by Mr. A. H. MacKay. 



As the unusual features of this sponge give it a peculiar import- 

 ance, I am tempted to copy the results of an entirely independent 

 study of it by my friend Mr. Carter, taken from a letter written to 

 the discoverer, Mr. MacKay. The comparison of it with that above 

 given may be both interesting and instructive, as showing how the 

 same peculiarities, equally new to both, may impress different ob- 

 servers. 



"Specimen sessile, spreading over two sides of a cubic stone about 

 two inches in diameter; about one sixth inch high in the center, 

 thinning off towards the circumference. Color of the surface 

 greenish; of the interior greyish brown. Surface smooth, shining, 

 (in the dried state), covering a parenchymatous structure beneath, 

 traversed by thread-like bundles of the skeletal spicules of the 

 species, charged with statoblasts. 



Statoblasts globular, of different sizes, but comparatively large 

 generally; being often /innyths of an inch in diameter; covered in a 

 tessellated manner, by a single layer of short fusiform spicules 

 in juxtaposition and all on the same level. 



