1887.] NATURAL SCIENCES OF PHILADELPHIA. 225 



of duplicate or triplicate series of birotulates around the gemmulse ; 

 that this feature was observed long ago, in the case of S. meyeni, 

 Carter, since merged with Meyenia fiuviatilis by the author ; and 

 that it did not seem to him nor does it appear to me to be specific, 

 though well worthy of notice. It may be questioned whether the 

 peculiarity would not be found in any siJecimens that had grown 

 where food or silica had been unusually abundant. 



(7) Meyenia (Ephydatia) bohemica, F. Petr. See "Diagnosis." p. 179. 



(8) Meyenia robusta, Potts. (PI. IX, fig. v.) 



Sponge massive, encrusting. Skeleton spicules subfusiform, 

 jwinted, smooth. . Gemmules scarce, birotulates of large size and 

 generally "monstrous" in form ; irregularly shaped, shafts abound- 

 ing in spines as long as, the rays of the rotulre, cylindrical or 

 conical. 



A large specimen of this species, if it be not properly a variety of 

 M. fiuviatilis, was found in the Museum of the Academy of Nat. 

 Sci. of Phila. marked, "presented by Dr. Geo. H. Horn ; collected 

 by him from Honey Lake Valley near Susanville, California." 



3Ieas. Skeleton spicules 0*01175 by 0*00055 inches. Length of 

 birotulates 0*00095 inches. Diameter of rotules 0*0008 inches. 



(9) Meyenia millsii, Potts. (PI. X, fig. ii.) 

 Sponge encrusting; texture loose. 

 Gemmulre spherical, small, surface smooth. 



Skeleton spicules nearly straight, cylindrical, slender, rather ab- 

 ruptly pointed, entirely microspined ; spines few, low, conical. 



Dermal spicules absent or undetermined. (A few minute forms 

 sometimes slightly curved, cylindrical but inflated near the middle, 

 may be only the initial condition of the birotulates before their disks 

 have been fully developed.) 



Birotulates surrounding the gemmules very numerous and sym- 

 metrical, their outer rotulte forming a smooth exterior to the gem- 

 mule. Shafts nearly cylindrical, but rapidly widening immediately 

 under the rotules ; frequently with a single spine near the middle. 

 Umbonate rotulse large, flat ; margins finely lacinulate, often mi- 

 crospined upon both surfaces. 



Meas. Skeleton spicules 0*0107 by 0*0005 inches. Birotulates 

 0*0012 by 0*00015 inches. Diameter of rotules 0*00075 inches. 



Loc. Collected from Sherwood Lake near DeLand, Florida, by 

 Henry Mills, Esq. 



