140 Tetr aphis Pellucida, Pellucid Four-toothed Moss. 



TETRAPHIS PELLUCIDA, PELLUCID FOUR-TOOTHED 



MOSS* 



BY M. Q. CAMPBELL. 



Mosses have a species of arithmetical progression which, as far 

 as we are aware, is peculiar to themselves ; and on examining 

 with the microscope the orifice of the little urn containing the 

 spores or seed, we shall find that some genera, as Sphagnum (Bog 

 Moss), Oymnostomum, Aucectangi/um, and Stylostegi/um (Beard- 

 h B Mosses) , etc., are destitute of the little circle of fringe which 

 we call peristome, or teeth. Next in arithmetical order will 

 come Tetraphia and TetoadonUwm, each possessing four teeth; 

 then I lie lesser Yoke Moss, and Mr. Forstev's Yoke Moss with 



eight teeth ; then many genera with a peristome of sixteen teeth, 

 others with thirty-two teeth, and cithers again with sixty-four. 

 But we BhaU Bearch in vain for any intervening numbers. 



The Tetraphia pell/udda, fruiting in this month, has heen 

 selected for our present consideration! Its generic name is 



* Ewplanation <>/ H<<- Cut, — Fig. 1. Tetraphia ptlUtoido, nat. size. Fig. 2. 

 Stem, ihowing crown of broadly ob-oordate Leavea surrounding the gemma of the 

 immature plant. Fig. 8. Oaptule, mag. ETig. 4. Oalypfcra, mug. Fig. 5. tad, 

 ma^. Fig. (! and 7. Lower anil upper leaves of the stem, mag. Fig. 8. Areola 1 , or 

 net-work of tho leaf, highly magnified. 



