PROGKESS OP MICROSCOPICAL SCIENCE. 251 



These imbibed water and expanded, and some of them in the course 

 of half an hour revived and exhibited their usual movements, but 

 others remained motionless to the last. The same slides were again 

 submitted to drying, and from one of them the cover glass was 

 removed. They were examined the next day, but several hours after 

 moistening them only two Eotifers were noticed moving on each slide. 

 He next prepared a slide on which there were upwards of twenty actively 

 moving Rotifers, and exposed it to the hot sun during the afternoon. 

 On examination of the slide the following morning, after moistening 

 the material, all the Rotifers continued motionless, and remained so 

 to the last moment. From these observations it would appear that 

 the Rotifers and their associates became inactive in comparatively dry 

 positions and may be revived by supplying them with more moisture, 

 but when the animals are actually dried they are incapable of being 

 revivified. Moisture adheres tenaciously to earth, and Rotifers may 

 rest in the earth, like the Lepidosiren, until returning waters restore 

 them to activity. — See also ' Silliman's Amer. Journal,' Sept. 



Neio Fresh-water Ithizopods have been recently observed by Pro- 

 fessor Leidy, who, in a jjaper before the Philadelphia Academy, 

 remarked that besides the ordinary species of Amceha, which he had 

 observed in the vicinity of Philadelphia, he had discovered what 

 he suspected to be a new generic form. It has all the essential 

 characters of Amoeba, but in addition is provided with tufts of tail- 

 like appendages or rays, from which he proposed to name the genus 

 Ouramoeha. The rays project from what may be regarded as the back 

 part of the body, as the animal always moves or progresses in advance 

 of the position of those appendages. " The rays are quite different 

 from pseudopods, or the delicate rays of the Actinophiyens. They 

 are not used in securing food, nor is their function obvious. The 

 Ouramoeha moves like an ordinary Amoeba, and obtains its food in 

 the same manner. The tail-like rays are not retractile, and they are 

 rigid and coarse compared with those of Actinophryens. They are 

 simple or unbranched, except at their origin, and they are cylindi'ical, 

 of imiform breadth, and less uniform length. When torn from the 

 body they are observed to originate from a common stock attached to 

 a rounded eminence. Several forms of the Ouramoeha were observed, 

 but it is uncertain whether they pertain to one or to several species. 

 One of the forms had an oblong ovoid body about ith of a line long 

 and xVth of a line broad. The tail-like rays formed half-a-dozen 

 tufts, measuring in length about the width of the body. The latter 

 was so gorged with large diatoms, such as Navicula viridis, together 

 with desmids and confervas, that the existence of a nucleus could not 

 be ascertained. The species may be distinguished with the name of 

 Ouramoeha vorax. A second form, perhaps of a different species, 

 moved actively and extended its broad pseudopods like Amoeba prin- 

 ceps. When first viewed beneath the microscope it appeared irregu- 

 larly globular and about -j^jth of a line in diameter. It elongated to 

 the ^th of a line, and moved with its tail-like appendages in the rear. 

 These appendages formed five tufts about aVth of a line long. The 

 interior of the body exhibited a large contractile vesicle and a discoid 



