198 PROCEEDINGS OP THE CALIFORNIA 



of five feet, the earth contained a large number of diatoms of the same species 

 as those obtained fro?n the spring — in fact, a large portion of the soil was com- 

 posed of diatoms, evidently formed in the water of the hot spring. From the 

 earth obtained to the south of the spring, few diatoms were found, and in these 

 but two or three were of the same species as those growing in the hot spring. 

 The time in which a s:nall surface like the outlet of the Pueblo hot spring, about 

 thirty yards long and two feet broad, would require to produce thousands of 

 cubic yards of this infusorial earth, almost transcends the power of the imagi- 

 nation to conceive ; and yet this process can only have been going on during 

 the present geological epoch, or since the surface of this portion of the globe 

 has been subject to any disturbance. 



The earth is made up of fine particles of clay and sand, with, he thought, fully 

 a third of diatoms. It also contains many silicious concretions, and as he is 

 convinced by the formation of the ground that these could not have been car- 

 ried there by water, he concluded that they must be silicified organic remains* 

 On making a thin section of one of these concretions, the microscope showed 

 that this was the case', a pair of legs of some coleopterous insect being plainly 

 visible in the quartz. The greater part of the concretion seemed made up of 

 petrified algce. It is impossible to say, without further exploration, how far 

 this deposit of diatoms extends. He hoped, however, to again have the oppor- 

 tunity of examining the place, when he would certainly endeavor to ascertain 

 the limits of this most interesting deposit. 



Dr. Kellogg read the following paper : 



Leptosyne gigantea Kellogg. 



BY A. KELLOGG, M.D. 



Root of woody structure, and like the stem, stout. Stem 2 to 8 feet high, 

 2 to 5 inches in diameter (concentric rings of annual growth, 3 to 8, each about 

 half-inch, pith about an inch), branches whorled, truncated, or abruptly termi- 

 nated, ultimate pedunculoid tertiary branches leafy, chiefly at the obtuse end 

 of secondary stems or branches. Leaves bipinnately divided, segments linear- 

 filiform, sub-spatulate, entire or sligb.tly emarginate, three-nerved ; glabrous, 

 fleshy, alternate, petioles stout, slightly expanded at the insertion, striate 

 nerved (6 to 9), 1 to 3 inches long, or a third of the lamina. Peduncles 

 alternate, often bracted, involucre double, outer series foliaccous, 5-7 linear ; 

 inner 1 2-1.0, membranaceous, colored (y.) ovate lanceolate, acuminate, nerved 

 16-20); receptacle convex; chaff membranaceous, colored (v.), oblanceolate 

 about 3-7 nerved, incurved, subconcave, deciduous with achcnia. Rays about 

 1.0, ligulate yellow, disk florets yellow, ring at the sunmiit of slender tube naked. 

 Achenia oblong or somewhat obovoid, obcompressed, slightly incurved, ob- 

 scurely 3 to 5 nerved, surrounded by a somewhat thickened, narrow marginal 

 wing, one-nerved on the inside; not a vestige of pappus upon the coroni- 

 form cup. 



The herculean proportion of this species at all stages of size, as seen upon 



