1887.] MATURAL SCIENCES OF PHILADELPHIA. 211 



(b) Margins of hirotulute sjncides rayed. 



5. Skeletoii spicules either smooth or microspined ; derraals want- 

 ing; birotulates short, shafts generally smooth; margins of rotules 

 irregularly rayed. (PI. V fig. v ; PI. IX figs, i, to iv.) 



M. fluviatilU. 



6. Birotulates in two or three series. M. (Ephydatia) mulleri. 

 (See also genus Pleiomeyeiiia.) 



7. Parasitic on S. lacustris; foramina funnel shaped. 



M. bohemica. 



8. Birotulate spicules generally malformed ; .shafts with enormous 

 spines, etc. (PL IX fig. v.) M. robusta. 



1). Birotulates rather long, shafts smooth ; margins of rotules la- 



cinulate. (PI. X fig. ii.) M. milhii. 



10. Rays an<l spines of birotulates subdivided or microspined. (PI. 



IX fig. vi.) M. subdivlsa. 



n. Dermal spicules with long, erect spines; l)irotulates long, 



spined; rays incurved. M. baileyi. 



12. Birotulates rather long; margins crenulate or granular. 



M. capeweUI. 

 18. Gemmules flask-shaped; apertures terminal; birotulates very 



short, obscure. M. anonyma. 



14. Shafts of birotulates much spined. M. ramsayi. 



15. Birotulates many times longer than the diameter of the hooked 

 rotules; shafts spinifevous. (PI. V, fig. vi. PI. X, fig. v.) 



M. crater if ormi.^. 



16. Gemmule birotulates long, club-like. Dermal spicules also 

 birotulate, minute. (PI. X, fig. iii and iv). 



31. everetti. 



17. Gemmule birotulates long, spinous; margins of rotules notched: 

 dermal spicules stellate. (PI. X, fig. vi.) M. plumo-m. 



(a) Mar(/i)if! of birotulate spicules entire. 



(1) Meyenia (Trochospongilla) erenaceus,' Ehrenburg, See Vfjjdovsky's "Ding- 

 nosis." ]>. 177 



In his description Prof. Vejdovsky has not, I think, invested the 

 parenchyma surrounding the gemmulse of this species with sufficient 

 importance. From specimens which he has kindly sent to me, I am 

 led to regard this feature, at least to this degree, as unique amongst 

 the sponges, and I regret my inability to furnish an illustration of 

 it. I do not know whether the sponge mass bears any external 

 resemblance to that of M. leidyi, but they are unquestionably distinct 

 species. 



