1887.] NATURAL SCIENCES OF PHILADELPHIA. 219 



without a suggestive guidance ; being about one sixteenth inch in 

 diameter. The first was found, accidentally, on a mount containing 

 another sponge and a very careful and almost despairing search 

 was required before another was discovered. Its generic classification 

 has been somewhat doubtful. But for its entirely abnormal gemmules 

 and the geographical dislocation of the sponges, it might readily 

 have been associated with the highest serial form of Tuhella jyenn- 

 sylvanica; viz., that in which the rotules are most nearly equal. 

 For the reasons mentioned it seems best to separate them and 

 place it in the genus Meyeaia, where it differs noticeably from M. 

 gregaria, (found upon the same stem) and from M. leidyi ; each of 

 which species has a capsular envelope ; also from 31. erenaceous Avith 

 its unique parenchyma of oblong cells. I have therefore made it a 

 new conditional species. 



(b) Margins of birotulates rayed. 



(5) Meyenia fluviatilis, (S. fluviatilis) Auct. (PI. V, fig. v, PI. IX, figs, i to iv.) 



Syn. European, See Vejdovsky "Diagnosis." p. 178. 

 " Asiatic, 1849, Spongllla meyem, Carter. 

 " American : 

 1875 Meyenia (Spongilla) asperima, Dawson. 



stagnalis, 



astrosperma, Potts. 

 polymorjiha, " 

 acuminata, " 



mexicana, " 



" " " angustibirotidata, Carter. 



" gracilis, 



'"Massive, lobate. Structure friable, crumbling. Color light yel- 

 low-brown. Skeleton-spicule curved, fusiform, gradually sharp- 

 pointed, smooth ; often spined and often centrally inflated, Stato- 

 blast globular; aperture infundibular; crust thick, composed of 

 granular or microcell substance, charged with birotulates whose 

 umbonate disks are deeply and irregularly denticulated, arranged 

 pai'allel to each other and perpendicular to the chitinous coat." 

 Carter. (Ann. and Mag. 1881 p. 92.) 



My observations upon this species as found abundantly in all 

 parts of North America, and in very variable forms, may be sum- 

 med up as follows. 



Sponge sessile, massive, rarely throwing out short branches an 

 inch or less in length. Color varying from light yellow or brown 

 to a light green, according to exposure. Surface tuberculated or 



