Mzviculacea.'} infusorial animalcules. 333 



verse, finely punctate, and cnrvecl strife; common on sea- weed, — as 

 Ceramium. Fossil at Cassel, North America, &c. Length 1-11 50th. 

 to l-240th. (fig. 162, 163.) 



CoccoNEis tmdulata. — Similar to the preceding, except in being 

 sculptm-ed with very delicate, concentric, undulating lines, instead of 

 transverse striaj. Length 1- 432nd. On sea- weed, Baltic. 



C. placentuh. — Plane, elliptic, smooth, Avith an abrupt margin. 

 Length 1-1 440th. In fresh water, upon Yaucheria and Lemna. 



C. pcdiculus. — Small, elliptic or oval, convex and smooth ; the disc 

 presenting a vciy fine longitudinal line, and the margin thi-ee lines. 

 Length 1 -2200th. to 1 -960th. Common on fresh water Algae. 



C. (?) Finnka. — Ovate, oblong, slightly convex; smooth exter- 

 nally, but stiiated within. Length l-570th. Fossil; Finland, 

 Mexico, &c. 



Var. (Jb.) — Larger, very elliptic, elongate, three to foar times 

 longer than broad. Length l-360th. Alive at the mouth of the 

 Elbe, and Antwerp. (P. 15, f. 41.) 



C. Americ-ana Smooth, with the habit of C. Iicxicana, but striae 



obsolete. Mexico. 



C. borealis. — Smaller, much elongated and elliptic, transversely 

 striated. = C. Islandica of Mexico. ^Iceland. 



C concentrica. — Small, broadly elliptic, ends widely rounded, and 

 Avith four concentiic longitudinal lines on each side. Mexico. 



C. decussata. — Larger, broadly elliptic ; rough, decussated by 

 rows of puncta, fapicuU ?J Cuba. 



C. elongata. — Smaller, smooth, ovate-elliptic, plane. Approaches 

 C. Plauniida, but is smaller; it, however, may be but a variety. 

 Massachusetts. 



C. fasciata. — Elliptic, larger, linear, with two longitudinal lines, 

 and a smooth transverse band at its middle. Peru. 



C. Leptoceros. = Rhaphoneis Leptoceros. — Still larger ; has the 

 habit of C. Ampldeeros, but its beaks much longer. 



C. longa. — Small, smooth, linear, rounded on each side. Iceland. 



C. Mexicana. — Rhomboid, punctate -striate, small ; ends obtuse, 

 and rather prolonged. It is small and more obtuse than C. Rhomlus. 

 Mexico. (P. 15, f. 48, «. b.) 



