426 APPENDIX. 



Cattegat, &c. This creature forms long zigzag bands, 

 which are fixed by mucus to algae and sertulariae. 

 Dr. Ehrenberg saw wands which were fourteen times 

 longer than they were broad, and some which were nearly 

 square. Theovaappear yellow or reddish -brown. Length 

 of fossil J -720th ; living, l-2300th to l-360th. 



744. Gramm ATOPHORA undulata.—WsLiads, when viewed 

 dorsally, quadrangular ; from the side, linear, and several 

 times undulated ; internal folds undulated. Found fossil 

 in the chalk marl of Greece, alive in sea water at Vera 

 Cruz. The live creatures are colourless. Greatest length 

 from two to three times its breadth ; the former 1 -860th. 



Genus Lithodesmium belongs to the Bacillaria, section 

 Desmidiaceae. The lorica is simple, univalved, siliceous, 

 and triangular in shape. Self-division imperfect, the 

 creatures being clustered in the form of straight and rigid 

 triangular-shaped wands; cluster unattached. 



745. Lithodesmium imdulatiim. — Corpuscles large, 

 smooth, and pellucid ; the angles obtuse. Two of the sides 

 are undulated, the others doubly excised ; openings and 

 motion are not perceptible. The corpuscles are somewhat 

 longer than they are broad. Found alive, in sea water, at 

 Cuxhaven. Greatest length of corpuscle, l-480th. 



Genus Podosira belongs to the Bacillaria, section 

 Echinaceae. Its members are fixed, the lorica beino- 

 pedicellate, bivalved, sub-rotund in form, and siliceous. 

 Self-division imperfect, and giving rise to moniliform chains. 



746. Podosira vummuloides. — Corpuscles globose, 

 slightly compressed laterally (discretis); body minutely 

 punctated. The pedicle is shorter than the diameter of the 

 body. The largest chains contained seven corpuscles. 

 The pedicle is colourless, the corpuscles green. Found 

 alive on a Polysiphonia in Peru. Size of corpuscle 1 -860th. 



Genus Triceratium belongs to the Bacillaria, section 

 Naviculaceae. The members are free, and have a bivalved 



