70 



SCIENCE 



[N. S. Vol. XL VI. No. 1177 



CARBONIFEROUS 



E. L. Moodie^" reprints, in his monograpli 

 of Pennsylvanian amphibia, descriptions and 

 figures of the remarkable microsaurs from the 

 Joggins coal fields in Nova Scotia, which 

 were published by Dawson between 1860 and 

 1895. 



TRUSSIC 



L. M. Lambe^" has published descriptions 

 of three new fishes, two Paleoniscids and one 

 Crossopterygian, from localities west of Banff. 

 The strata have heretofore been assigned to 

 the Jurassic period^' but are more correctly 

 correlated with the Upper Banff shale on the 

 basis of invertebrates associated with the fish 

 remains. The Upper Banfi fauna, according 

 to Girty and Kindle, represents the horizon 

 of the Lower Triassic Meekoceras beds of 

 Idaho and Wyoming. It should no longer be 

 referred to the Permian. 



CRETACEOUS-EOCENE 



The geology of the region about Wood 

 Mountain and Willowbunch, adjoining the 

 international boundary south of Moosejaw, 

 Sask., is described by Bruce Bose.^^ The 

 strata exposed range from the Pox Hills and 

 Pierre Cretaceous through the Lance forma- 

 tion to the Port Union Eocene. The latter 

 contains lignitic coal of value. An excellent 

 description of the Prairie Plains of Saskat- 

 chewan and their Quaternary history forms 

 the second chapter of the report. 



ISTew types of duck-bill dinosaurs from the 

 Cretaceous of Alberta are described by 

 Brown.i" 



15 R. L. Moodie, ' ' The Coal Measures Amphibia 

 of North America," Carnegie Inst. Washington, 

 Pub. 238, 1916. 



18 L. M. Lambe, ' ' Ganoid Fishes from near 

 Banff, Alberta," Trans. Boy. Soc. Canada, Ser. 3, 

 Vol. 10, See. 4, pp. 35-44, 1916. 



IT J. A. Allan, ' ' Bankhead to Golden, ' ' Cong. 

 g6ol. internat., Guide Book 8, Pt. 2, p. 191, 1913. 



13 Bruce Eose, ' ' Wood Mountain- Willowbunch 

 Coal Area, Saskatchewan," Geol. Surv., Canada, 

 Mem. 89, 1916. 



19 Barnum Brown, American Mus. Nat. Hist., 

 BuU., Vol. 35, pp. 701-708, 1916. 



MIOCENE 



A new species of cyprinid fish, based upon 

 four specimens discovered by Bruce Eose of 

 the Canadian Geological Survey near Kam- 

 loops Lake, B. C, is described by Hussakof.^" 

 It has considerable resemblance to Leuciscus 

 halteatus living to-day in the Columbia basin. 

 KiRTLEY P. Mather 

 Queen's TIniversitt, 

 Kingston, Canada, 

 March 5, 1917 



SPECIAL ARTICLES 



THE VITALITY OF CYSTS OF THE PROTO- 

 ZOON, DIDINIUM NASUTUM 



It is well known that many of the unicel- 

 lular forms encyst under certain conditions, 

 i. e., become inactive and form a heavy wall 

 about themselves, and that in this state they 

 can endure environmental conditions which 

 are otherwise fatal. For example, the loss of 

 water readily kills didinia when they are in 

 the active state, but when they are encysted 

 desiccation such as is produced by exposure 

 even for months to ordinary atmospheric con- 

 ditions does not necessarily kill them. This 

 is also true of many other forms. When they 

 are thus dried they may be widely scattered 

 by the wind; encystment consequently may 

 have a twofold function, protection and dis- 

 tribution. Whether or not it functions still 

 further in rejuvenescence in accord with the 

 contention of Permor (1913) and Calkins 

 (1915) is a question which will be considered' 

 at some length in a later paper. 



The degree of protection and the extent of 

 distribution that organisms secure by encyst- 

 ment depends upon the vitality of the cysts. 

 The longer they live the greater the protec- 

 tion and the wider the distribution. It is 

 consequently important to know how long 

 organisms can live in the encysted state. 

 This is esi>ecially true regarding pathogenic 

 forms, and these forms are the only ones, with 

 the exception of the rotifers, in which the 

 problem has been seriously investigated. 

 Knowledge regarding the endurance of cysts 



20 L. Hussakof, "A New Cyprinid Fish, Leucis- 

 cus rosei, from the Miocene of British Columbia," 

 Am. Jour. Sci. (4), Vol. 42, pp. 18-20, 1916. 



