IOWA ACADEMY OF SCIENCES. 



15 



the form of a shallow polypronal calyx. Each was united to the center of the sphere, 

 the point at which growth began, and from which it proceefled outward along 

 radial lines, by a slender thread of protoplasm which was also inclosed in a 

 delicate chitinous sheath. The colony was free, and doubtless moved through the 

 water with the graceful rolling motion that characterizes colonies of Uvella and 

 Si/nura. The movements of the still more beautiful and much more familiar 

 Volvox globator will convey to users of the miscroscope a correct idea of a mode 

 of locomotion I fancy they might have wit- 

 nessed, without the aid of the "tube," in all 

 the sheltered covers of the Upper Silurian 

 period where Cerionites congregated. It is 

 probable that the skeleton was chitinous rather 

 than calcareous. It was flexible enough to 

 undergo extensive deformation without break- 

 ing, and exposed parts were frequently de- 

 composed before the entire structure was 

 embedded. 



The zoological position of Cerionites is less 

 clear than the structure of its skeletal parts. 

 It is scarcely probable, however, that the 

 Ideal section of Cerionites (orig- ^^^j^^ ,j^^^ inhabited the delicate chitmous 



^°''^^'' thecse, attained the rank of Hydrozoa. Ifc 



seems more probable that they were rather gigantic Piotozoa. At all events I 

 know of nothing to render such a view improbable. Some of our modern protozoa 

 are about as large as the smaller individuals of Cerionites. Individuals of the 

 genus Noctiliica are often a twentieth of an inch in diameter, and the gigantic 

 Actinosphceria to which I called attention in ihe American Naturalist for 1890 (Vol. 

 25, page 934), are even larger. Many of the Protozoa secrete a chitinous case or lorica. 

 Many, as Urella and Si/nurn, live in spheroidal colonies in which the individuals 

 are attached by bands of more or less modified protoplasm, to the center of the 

 sphere, and in Si/nura, each zooid is contained iu a separate membranous sheath 

 which takes the form of calices here conceived to have been present in Cerionites. 

 Figures 12 and 18, plate i of Kent's Manual of the Infusoria, representing 3/f.(7os- 

 phcera planula. approximate very closely the figures that must be made to express 

 my conception of a living colony of Cerionites. The figure accompanying this 

 paper is simply an attempt to represent diagramatically an ideal section of such 

 a colony. 



wm^ 



NATURAL GAS AND OIL IN IOWA. 



BY CHAKLES ROLLIN KEYES. 



During the past decade no geological question has awakened more popular inter- 

 est than that of the possibility of finding natural gas and petroleum within the 

 limits of the State. In a number of places shallow borings have yielded from time to 

 time sufficient quantities of natural gas lor local use. At some of these places the 

 citizens are kept constantly in a feverish state of expectancy which is ever ready to 



