INSTITUTE OF SCIENCE, PHILADELPHIA. 7 



of the serpulae ; to the upright positions of the spicular armature of these 

 genimulje (resembhng in this respect certain lacustrine forms ah'eady 

 described, as found upon the Catstcill Mts., N. Y., at White Haven, Pa., and 

 at May's Landing, N. J., and in strong contrast with the idea of a typical 

 tangential position) ; and to the striking resemblance of these spicules to 

 those of Spoiigillafragilis, rather than to the corresponding spicules of any 

 form of vS. lacitstris. 

 Spoagilli Wigneri. N. sp. 



Sponge (as examined), white ; incrusting, thin. Proper skeleton texture 

 loose and open, but entirely hidden by a compact layer of dermal spicules 

 upon the outer surface, where they crowd even to the projecting points of 

 the skeleton spicules, thus presenting a comparatively flat but greatly 

 roughened surface. 



Gemmules rather abundant within the lower layers of the skeleton 

 spicules or, more generally, hidden away within the cavity of the barnacles 

 or amongst the coils of the serpula upon which the sponge has grown. 

 Chitinous body relatively small, but surrounded by an extremely thick 

 granular crust, charged with an abundance of unusually long gemmule 

 spicules, erect, but crossing each other's lines in every direction. 



Skeleton spicules long, robust, smooth, fusiform, slightly curved ; grad- 

 ually sharp-pointed. 



Dermal spicules excessively abundant, both upon the outer and inter- 

 stitial surfaces ; long, slender, delicately pointed, curved, entirely spined ; 

 spines erect, cylindrical, round-ended, longest near the middle of the spicule. 



Gemmule spicules relatively long, cylindrical, irregularly curved, entirely 

 spined ; spines acute, erect ; distant along the body of the shaft, often 

 recurved and more numerous at the extremities of the spicules, where they 

 form a head or bur. 



Measurements : Skeleton spicules, 0.0144 inches long by 0.0007 inches 

 thick ; length of dermal spicules, 0.0049 inches ; of gemmule spicules 

 0.0048 inches. 



