APPENDIX. 189 



forms now living in our bogs, and constitute a large portion of the recent fresh-water deposits of 

 infusorial shells. 



" With the infusorial shells are found considerable numbers of Spongiolites, the siliceous 

 spiculse of fresh-water sponges. Several forms of these bodies are represented in the figures 

 from 14 to IS inclusive. They are cylindrical, generally tapering at both ends, and traversed 

 by a central canal. Some present a smooth exterior, others are covered with numerous protu- 

 berances which are themselves hollow ; such is the case in Fig. 18. Sometimes the central 

 canal is very narrow, appearing like a mere line, as in Fig. 14 ; in others it is very wide, as in 

 Fig. 15. These bodies are common in the recent infusorial deposits. 



" In Fig. 9, a and b represent two positions of a minute spherical body, having a short neck. 

 These appear to be hollow, and are present in considerable numbers. Similar forms occur 

 abundantly in the recent deposits of our bogs ; but their nature is unknown. 



" In Figs. 12 and 13 are given outline sketches of two Pollen granules. These are of fre- 

 quent occurrence in the marl, and have the characters of the pollen of the Coniferas. 



" Professor Bailey has given, in a paper on Infusoria (Silliman's Journal, vol. xlviii. p. 239), 

 the results of a microscopic examination of the marl from Scotchtown, Orange County, N. Y., 

 in which was found a fine head of the Mastodon [the Shawangunk Head. — Ed.]. He states 

 that the marl contains numerous fresh-water shells of recent species, among which are several 

 common species of Planorbis, Cyclas, and Limnea ; some still retaining the epidermis. 



" He prepared the marl for the microscope by the same process which occurred to me, and 

 detected several species of siliceous-shelled infusoria, among which he names some of those 

 found in the present specimen. Besides these, he mentions a single membranaceous species 

 (Closterium Crenulatum), Spongiolites Lacustris, pollen of pine, stellate hairs of Platanus (?), 

 and seed-vessels of Nitella or Chara. 



" He says, ' These results are interesting, as they prove, first, that siliceous infusoria, iden- 

 tical with those now living, were contemporaneous with the Mastodon.; second, that not only 

 siliceous but membranaceous infusoria, hairs of plants, &c, may be preserved for ages in calcare- 

 ous marls, where they may be detected after the calcareous matter is dissolved by acids.' 



" I have not attempted to name definitely the species of infusoria detected in the marl, as 

 the present state of microscopic science does not allow of a settlement of the question with 

 regard to the identity of living species with those of any past geological period." 



