1866.] 77 [Stoddor. 



and SIX internal teeth. Some others that do not correspond exactly 

 to any of Ehrcnberg's species, were also found. 



There are several varieties of sponge spicules, not very abundant. 

 It is not worth while to describe the variation in shape of these things, 

 until some one has made a study of them, and shown the connection 

 between forms of spicula and specific character of the sponge. 



Diatomacese. 



This order of Aljce is well represented, constituting eight to nine- 

 tenths of the bulk of the deposit. The combination of species is 

 quite remarkable, in some respects resembling the Monterey deposits. 

 The most abundant form, and the lai-gest also, is Coscinodiscus aster- 

 omphalus Ehr., a beautiful species, varying from .0033 to .01 of an 

 inch in size. It is so plenty that it must, I judge, compose about one- 

 half of the whole bulk of the deposit. There are a vast number of 

 very minute forms, both circular and bacillar, so minute that even 

 with a power of thirteen hundred diametei-s, no reliable specific char- 

 acters can be demonstrated. Such small forms are not uncommon in 

 other fossil deposits, but here they are far more numerous than I have 

 ever met with elsewhere, as in numbers they exceed all the others. 

 Several specimens of Euodia gibba have been found. This Is a genus 

 named by Prof. J. W. Bailey from a form found by him in the Atlantic 

 Ocean ; not published by him, but by Ralfs. I do not know that it 

 has ever been found by any other writer, unless the Hemidiscus of 

 Walllch is the same. Some observers have found it in muds from the 

 Gulf of Mexico.* Some of the specimens here are Identical with 

 Bailey's, but others are more convex on the least convex side, and 

 want the constriction near the ends. I am, however, unwilling to 

 make a species on such variations of outline. 



The species of Actinocyclus, ActmoptijcTius and Omphalopelta are 

 abundant, but the specific characters of the three genera are often so 

 indefinite that it is difficult to assign names to them. The list of other 

 genera and species found, is quite large, but with the remarkable fact 

 that the individuals are very rare ; of the list more than one-half is 

 represented by a single specimen only, and of the other half but very 

 few have been found ; of some not more than two. No other fossil de- 

 posit that I have examined has ever given such a result — so many 

 very scarce forms. Not less remarkable is the geographical distribu- 

 tion of these forms. They have representatives in California, Virginia, 

 Florida, Scotland, Spain, the Pacific, Atlantic and Indian Oceans. 

 It is rather remarkable that several species have been published 



* Since the above was written, it has also been found by Mr. Greenleaf in sound- 

 ings in the Gulf Stream off Cuba, with variations from Bailey's typical form 

 similar to those mentioned here. 



