﻿Prof. Bailey on Fossil and Recent Infusoria. 337 



Dictyocha Fibula, Gallionella sulcata, Rhaphoneis Rhombus, 



Triceratium Reticulum, &c. 



4 There are a great number of fossil species at these localities, 

 which, although very easy to be recognized, have never been 

 found in a recent state, and are therefore probably extinct. 



5. On the other hand there are numerous well characterized 

 recent species which are every where present in the deposits of 

 our present seas, which have never been found in the fossil state, 

 although they are so large and well marked that it would be im- 

 possible to overlook them if they were present. Among these 

 may be mentioned Biddulphia pulchella, Isthmia obliquata, Tri- 

 ceratium favus, Gallionella moniliformis, Tessella catena, Ach- 

 nanthes brevipes, Cocconeis oceanica, &c. These are therefore 



probably of recent creation. 



6. It hence appears that the same successive extinction of some 

 species and creation of others, which has taken place with regard 

 to the larger tribes of organic beings, has also occurred with the 



most minute races. 



7. The specimens from all the above localities agree in the total 

 absence of the calcareous-shelled Polythalamia, although these 

 calcareous forms are very abundant in the associated beds m 

 which the shells of mollusks are found in an undecomposed state. 



IV. Recent Infusoria in the Blue Mud of New Haven Har- 

 bor.— -This mud, which is used I believe as a fertilizer, was re- 

 cently analyzed by B. Silliman, Jr. and the following results ob- 



tained. 



Silica, 

 Alumina, . 

 Oxide of iron, . 

 Carbonate of lime, 

 Magnesia, 



58 633 



30563 



6-186 



4-263 



0-705 



100 348 



Some of the same mud was given me by Mr. Silliman, with 

 the request to examine it by the microscope. The contents 

 which I found were as follows— viz. particles of quartz, horn- 

 blende, and feldspar, mingled with great numbers of siliceous 

 infusoria, among which were noticed Actinocyclus senarius, Cos- 

 cinodiscus excentricus, C. oculus-iridis, Cocconeis oceanica, Dtc- 



tyocha speculum, D. Fibula, Dicladia ? Eunotia Uester- 



manni, Gallionella sulcata, Grammatophora oceamca, Fmnu- 



