212 PROCEEDINGS OF THE ACADEMY OF [1887. 



(2) Meyenia leidyi, Carter. Ann. and Mag. 1881, p. 91. ( PI. V. fig. iii. PI. X, fig. i.) 

 Spongilla leidxji, Bk. (Proc. Zool. Soc. 1863, p. 445 etc.) 



"Sponge sessile, coating, thin ; surface tuberculated, minutely his- 

 pid ; oscula numerous, small, congregated, elevated and marginated ; 

 pores cons])icuous. Skeleton spicula acerate, small, short and stout, 

 rather obtusely terminated. Dermal and interstitial membranes 

 aspiculous. Ovaria spherical, small ; dermal spicula birotulate, 

 minute, short ; shaft cylindrical ; rotulse margins entire, that of the 

 outer one sometimes exflected and rarely spiculated."(?) Bowerbank. 



The above is Dr. Bowerbank's original description after the ex- 

 amination of one dry specimen. During the past six years I have 

 collected the .species, scores of times and perhaps in greater quantity 

 than any other. I will describe it as I have seen it. 



Sponge of a peculiar light gray or drab color, even when exposed 

 to the light ; encrusting, thin. Persistent ; the growths of success- 

 ive seasons forming as many series of thin lamina. Surface even, 

 sometimes rising into smooth rounded prominences, and at times 

 covered with singular radiating or bird-track-like markings, whose 

 cause is not fully understood. Pores and osteoles numerous, min- 

 ute ; the latter being found along the radiate lines, but not conspic- 

 uously at their confluence. Texture very compact ; composed of 

 short spicules, very slightly fasciculated ; the primary lines and 

 ])rincipal channels nearly perpendicular ; with single intercalating 

 spicules forming polyhedral interspaces. 



Gemmules numerous, sub-spherical, deposited at the base of the 

 sponge and, in successive seasons, in serial layers above (or below ?) 

 the first. Eacli mature gemmule is surrounded, outside of the bi- 

 rotulate armature, by a lattice work or capsule, composed of spicules 

 resembling those of the skeleton ; an open space being left at 

 the top around the short, tubular foramen (PI. V, fig, iii. A). 

 When more than one of these is present, they are grouped together, 

 and the open space of the capsule is correspondingly enlarged. Be- 

 fore maturity a granular crust embeds and surrounds the dense 

 layer of sliort birotulates, but after the latticed capsule is formed, 

 (at least when examined in a dry state) I have not been able to dis- 

 cover it. 



Skeleton spicules short, smooth, robust; Avhen mature very ab- 

 ruptly terminated, almost rounded. (PI. X, fig. i, a,a,a,b,b.) 



Dermal and interstitial surfaces aspiculous. 



