GENUS TEINEMA— TRINEMA ENCHELYS. 227 



Arcella Megaatoma. Ehrenberg: Monatsb. Ak. Wis. 1853, 182; 1856, 337, (Tafel) Fig. 3. Mikrogeologie, 



1854, Taf. xxxiv, viii, Fig. 1. Abh. Ak. Wis. 1871, 259. 

 Euglypha pleurostoma. Carter: An. Mag. Nat. Hist. 1857, xx, 35, pi. i, figs. 19 a-i. 

 Euglypha Enchelya. Wallieh : An. Hag. Nat. Hist. 1864, xiii, 245, pi. xvi, figs. 46, 47. 

 Arcella roetrata. Ehrenberg: Abb. Ak. Wis. 1871, 272, Taf. iii, U, Fig. 2. 

 Arcella reticulata. Ehrenberg: Ibidem, Fig. 5. 

 Arcella seriata. Ehrenberg: Ibidem, Fig. 6. 

 Arcella Pyrwm. Ehrenberg : Ibidem, Fig. 15. 

 Hommochlamya conatricta, U. Disphcera, E. Enchelya, H. hyalina, and S. roatrata. Ehrenberg: Abb. Ak. 



Wis. 1871, 244. 

 Stieholepia caudicicola, S. A'idua Pendulua, and S. Megaatoma. Ehrenberg : Ibidem. 

 Beterocoamia Pyrum. Ehrenberg: Ibidem, 245. 

 Trinema enchelya. Leidy: Pr. Ac. Nat. Sc. 1878, 172. 



The only species of the genus. 



Size. — Ranging from 0.016 mm to 0.1 mm. long by 0.01 mm. to 0.0G 

 nam. broad, and mouth from 0.005 mm. to 0.024 mm. in diameter.* 



Locality. — Sphagnous swamps, wet forests about the roots of mosses, 

 in marshes, and in the ooze of pools and ponds. 



Trinema enchelys is one of the commonest and smallest of the shell- 

 bearing rhizopods, and is found almost everywhere in moist places as well 

 as in pools and ponds. It is especially abundant in sphagnous swamps, 

 but is often found in the earth about the roots of mosses and other plants, 

 even in such places as roadsides, on the bark of trees, old wooden or thatched 

 roofs, and in the crevices of pavements of cities. It was originally described 

 by Dujardin under the name of " Trinerne," and it was not until after the 

 publication of Ehrenberg's 'Infusionsthierchen,' in which it is described 

 and figured as Difflugia Enchelys, that the former called it Trinema acinus. 

 Though the latter name is employed by most subsequent writers, according 

 to the rules of zoological nomenclature the one I have adopted at the head 

 of this chapter is the proper one. 



Trinema enchelys is very variable in form and size, and thus helped 

 Ehrenberg to swell the long list of his Difflugias and Arcellas. See pi. 

 XXXIX. The shell is colorless, transparent and pouch-like, with the oral 

 end usually the smaller. The mouth opens downward beneath the oral 

 extremity, and the inflated fundus of the shell is directed obliquely back- 

 ward and upward. 



In the full view of the shell, beneath, its outline is usually more or less 



* The measurements are taken from the view of the shell beneath, giving the extreme length from 

 the edge of the shell in advance of the mouth to the summit of the fundus, while the breadth indicated 

 applies to the latter. 





