OF THE ANIMALCULES OF THE RED SNOW. 85 



seen from above, the body extended as in the ordinary act of progression on 

 the bottom or side of the vessel in which it is kept. The three principal 

 regions of the body are very distinct : 1 . The head and neck, with the 

 different organs of sense, and the commencement of the digestive sys- 

 tem ; 2. The trunk, which is nearly cylindrical, and is enveloped in a 

 furrowed cutaneous carapace ; 3. The articulated feet. 



The anterior extremity, with its cilia, is expanded as in the act of 

 touching ; the rotatory organs are contracted : a little posterior to these 

 may be seen in the median line, the respiratory tube, which is equally 

 contracted, when spread out, it is much longer, and is furnished at its 

 extremity with stiff cilia. Behind this tube the eyes are met with, 

 which are obliquely placed ; they are colourless in the variety from the 

 Alps, whilst they are red or yellow in the common variety. Next comes 

 the pharynx, with its two teeth, from whence the intestinal canal pro- 

 ceeds, which, in the figure given by Dr. Vogt, is of a blue colour, the 

 animal having been fed on indigo. The intestinal appendages are distin- 

 guished from the ovary by their intense red colour. The foot, capable of 

 expansion and contraction, is also seen. It is composed of seven rings ; 

 the fifth and sixth are armed with two points, the seventh is furnished 

 with two claws, very much analogous to the posterior feet of the Che- 

 nilles. On either side of the body may be seen, in four different places, 

 the organs which Ehrenberg described as vibratile branchiae, but which 

 in reality are nothing more than enlargements of two lateral vessels given 

 off from the respiratory tube, and furnished with cilia. Similar vibra- 

 tile enlargements are seen at the union of the neck with the body, in 

 two situations in the middle of the body, and one at the side of the 

 anus. The head and neck, as well as the feet, may be withdrawn into 

 the coriaceous carapace of the body, which is susceptible of considerable 

 dilatation and contraction. Fig. 2 represents those imperfectly deve- 

 loped eggs which have been mistaken for Protococcus. Fig. 4 shows 

 the form of the winter-eggs not developed, with the covering in the 

 form of a rosette ; both the one and the other are met with in red snow. 

 Fig. 3 represents an accumulation of the ordinary eggs of Philodina, 

 collected from the crevices of the polished surface below the glacier of 

 Rosenlain ; the number is by no means limited. 



The red snow of the upper glacier of the Aar and that of Siedel- 

 horn, furnished us with Philodinas and eggs of different forms, similar 

 to Protococcus. The lower glacier, and that of Finsteraar, presented 

 us with all the organisms noticed in this communication. 



