1885.] PKOCEEDINGW OF IJiMTKI) .STATED IsATlUNAL MU«EUM. 587 



FRESH- WATER SPONGES FROM MEXICO. 



By ES^VAKD I»<>TTS. 



Meyenia plumosa, Carter, vtir. Palmeri, n. v. 



Spongfe (as seen iu a dry state) dark brown, massive, attached to and 

 snrrounding tlie dependent branches of small trees, whose stems are 

 flooded by the spring freshets. Textnre verj' loose, and when dry so 

 brittle that the dermal snrface cannot be satisfactorily examined. (The 

 impression conveyed hy the interior appearance of this sponge is that 

 it is made up of an infinite number of radiating confluent branches.) 



GemmulfB large, numerous throughout the deeper portions of the 

 sponge; subspherical or ovoid, surrounded by long birotulates imbedded 

 in agranular crust. 



Skeleton spicules straight or slightly curved, mainly cylindrical but 

 gradually sharp-pointed, sparsely microspined. 



Dermal spicules irregularly stellate as in the typical species, but in 

 the specimens examined much fewer in number. They vary from sim- 

 ple acerates with one or more long divergent branches to beautiful ra- 

 diate splierical bodies whose rays are nearly equal, spined, and capitate 

 by reason of recurved spines at their extremities. Another form of 

 spicule, probably also dermal, of which several are seen upon nearly 

 every slide prepared for microscopic examination, is very difficult of 

 descriptiou. It may be said to be composed of an irregular series of 

 smooth curved rays arising from a nearly common center, and is some- 

 what suggestive of a hedgehog or Scotch terrier. 



Birotulate spicules pertaining to the gemmuLT, in length about three 

 times the diameter of the supi)orted rotules; shafts cylindrical, plenti- 

 fully spined; spines long, conical. 



in- 





Outer surface of rotules convex, 

 margins lacinulate; ends of 

 complete rays obtuse, recurved. 



Sponge masses subspherical, 

 reaching five or six inches in di- 

 ameter. 



The plate represents: a, skele- 

 ton spicule ; h, c, c, birotulate spic- 

 ules of the gemmule; d, d, ends 

 or rotules of the same; e, e, e,f, 

 dermal spicules; g, g, abnormal 

 forms frequently observed. The 

 spicules are magnified 200 diam- 

 eters. 



This spoDge, collected by Dr. Edward Palmer along the banks of the 

 Colorado Eiver, near Lerdo, Sonora, in Northwestern Mexico, about 



