1887.] NATURAL SCIENCES OF PHILADELPHIA. 203 



supporting surface. These groups are approximately hemispherical 

 in shape, resting upon a -flat subcircular side or base, above which 

 they form a dome-shaped mass suggesting a resemblance to the 

 igloe or hut of an Eskimo (PI. V, fig. iii. A.). The foraminal ap- 

 ertures of the gemmules composing these groups, contrary to their uni- 

 form habit in S. fragilis, all open inward, apparently communicating 

 with a central cavity within the mass or group. Each gemmule, 

 as in the last named species, is enveloped in a cellular parenchyma, 

 which also, by short isthmus-like bands, connects it with the adjoin- 

 ing gemmules and finally compacts the members of a group together; 

 but, Avhereas the parenchymal cells of S. fragilis are nearly uniform 

 in size, these are very variable, being large upon the superfices of 

 the gemmule proper and upon the outer surface of the envelope ; 

 while the interior cell-structure is with difficulty resolvable under 

 a one-fifth objective. This parenchyma is densely charged with 

 echinating spicules. 



Skeleton spicules very few, sub-fusiform, but somewhat enlarged 

 near the terminations, then abruptly pointed or rounded ; sparsely 

 microspined ; spines short, obtuse. (PI. VIII, fig. v, a.a.) 



Gemmule spicules exceedingly numerous, nearly as long as those 

 of the skeleton ; sub-fusiform, abruptly pointed, entirely spined. 

 Spines long, acute ; perpendicular at the middle of the spicules 

 while those near either end are strongly recurved. (PI. VIII, fig. 

 V, b.b.) 



Meas. Skeleton spicules 0.0099 by 0.0004 inches; gemmule spic- 

 ules 0.00657 by 0.0004 inches. 



Hab. Upon the lower side of timbers etc. in Cedar swamps near 

 the East coast of New Jersey. 



Log. Collected as yet only near Absecum and Vineland 

 N.J. 



The points of difference between this species and S. fragilis seem 

 obvious. I find them in the spinous character of the skeleton spic- 

 ules ; in the want of fibrous structure in the sponge itself; in the 

 different characters of the gemnmle spicules ; in the absence of a 

 pavement layer of gemmules ; in the peculiar flat-sided arrangement 

 of the groups and in the fact that the germinal apertures all open 

 inward. 



This sponge was discovered during a memorable visit to Doughty 's 

 Pond, Absecum, New Jersey, December 1st. 1883. The locality has 

 been described in the general remarks under the head of Spongilla 



