34 TRANSACTIONS OF THE [NOV. 4, 



There is anotlier group of mineral remains which offers much 

 more difficulty to a direct diagnosis, but which numerically, in 

 our latitude at least, is much more important than the preceding 

 ones. Ill the living specimens, possessing a very attractive 

 system of organs and charming ])rincipally by a disjjlay of their 

 various functions, the skeletons form only a secondary part. But 

 in the buried remains the skeletons, occurring in great abun- 

 dance, come to the foreground. Tliey are white, almost trans- 

 lucent ; they have a well-defined, generally angular contour, and 

 are only identified by the practised eye. These remains are de- 

 rived from the following groups : — 



(/) Ciliata. 



(a) Heterotricha — Coleps, Freia, etc. 



(/3) llypotricha — Eujilotes, Aspidisca, Ervilia, Trochilia, 



Ciilamydodon, Uronychia, etc. 

 (;/) Peritricha. The family of the Vorticellida3 is the most 

 important ; those with a vaginal mineral envelope — 

 VagiuicolcG — are Cothurina, Vaginicola, Planicola, 

 Opercula, Stylocola, etc. 



iff) Acineta3. 



The only mineral remains yet to be mentioned are : 



(A) Sponges — spicula^ and needles. 



(i) Skeletons of rotatoria and Crustacea. 



This biological detritus, which in nature is formed on a very 

 large scale, is the substratum, out of which the so-called infuso- 

 rial or diatomaceous earths have been formed. I propose the term 

 protozootite as more appropriate for this group of rocks, com- 

 posed of biological detritus, the largest percentage of which be- 

 longs to the Protista family, — Haeckel's group of Protista in- 

 cluding the Protozoa, as formerly classified. It will readily be 

 understood that the chance of observing this biological detritus 

 unaltered, as originally dumped during its process of formation, 

 is seldom offered, and that my surprise at what I saw under the 

 microscope in examining the ferruginous protozootite was indeed 

 very great. The porosity and hygroscopic ])0wcr of this rock ex- 

 plain the remarkable freshness of its state of preservation. It 

 contains, in fact, miscellaneous biological detritus; but the 

 organic ingredients — vegetable or excrementitious — are jiredo- 

 niinant. Chlorophyll is well preserved, especially in Euglcna, 

 also spores of diatoms. A small fragment heated in the closed 

 tube yields water, givesa white sublimate and thick yellow drops; 

 an empyreumi'.tic odor is very perceptible ; it blackens com- 

 pletely, but is not magnetic; the genesis of this ferruginous 

 protozootite is therefore fully explained. 



Protozootites are not uncommon in California, especially in 

 the Coast Kange. Not far from the locality where this ferru- 



