FOSSIL AND LIVING SPONGES. 709 



fathoms, on the west side of Barbadoes, alive, 

 and kept it alive for twenty-four hours, dur- 

 ing which time the animal expanded and 

 showed its remarkable peculiarities. It is un- 

 questionably the type of a distinct family, en- 

 tirely different from the other Mollusks with 

 which it has been hitherto associated. Mr. 

 Blake has made fine colored drawings of it, 

 which may be published at some future time. 

 . . . The family of the Pleurotomariae num- 

 bers between four and five hundred fossil spe- 

 cies, beginning in the Silurian deposits, but 

 especially numerous in the carboniferous and 

 Jurassic formations. 



The sponges afford another interesting case. 

 When the first number of the great work of 

 Goldfuss, on the fossils of Germany, made its 

 appearance, about half a century ago, the most 

 novel types it made known were several gen- 

 era of sponges from the Jurassic and creta- 

 ceous beds, described under the names of 

 Siphonia, Ghemidium, and Scyphia. Nothing 

 of the kind has been known among the living 

 to this day ; and yet, the first haul of the 

 dredge near Barbadoes gave us a Chemidium, 

 or, at least, a sponge so much like the fossil 

 Chemidium, that it must remain for future 

 comparisons to determine whether there are 



