356 PROF. EHRENBERG ON ANIMALS OF THE CHALK 
Odontelle curvatee EHucampie formam referunt, sicut Fragilarie 
curvate Meridii fere characterem pre se ferunt. 
The only known species of this genus is represented on Plate VIII. | 
V. GrammatorHorA.—Char. gen. Animal polygastricum e familia 
Bacillariorum, sectione Naviculaceorum, liberum (sepe implexum, 
nec affixum) lorica simplici bivalvi (silicea) et prismatica, spontanea 
imperfecta divisione in catenas dehiscentes flexuosas abeunte, Tabel- 
lariam equans, ab eaque dissepimentis duobus internis, tres loculos 
longitudinales formantibus, diversa. 
Tabellariam refert plicis duabus internis siliceis, seepius ad scrip- 
ture modum flexuosis, insignem. 
Five species of this genus are known, of which three have occurred 
in Oran and one in Greece ina fossil state. All three from Oran 
have been observed alive in the North Sea, one of them likewise in the 
Baltic, in the Mediterranean, and on the coast of Peru: the Greek 
form has been detected alive on the Mexican coast. The fifth species 
has been found only in the living state from the bay of Mexico. 
VI. Lirnopesmium.—C/iar. gen. Animal polygastricum e Bacillari- 
orum familia, ejusque Desmidiaceorum sectione, liberum, lorica sim- 
plici univalvi triangula (silicea), spontanea imperfecta divisione in 
bacilla rigida triangularia recta abiens. 
Characteres Desmidii, sed lorica triangula silicea sub cute sponte 
divisa. ? 
The only species of this form inhabits the North Sea; a represen- 
tation of it is given on Plate VIII. 
VII. Popostra.—Char. gen. Animal polygastricum e Bacillariorum | 
familia et Echinelleorum sectione, affixum, lorica pedicellata bivalvi 
subrotunda (silicea), spontanea imperfecta divisione monilia formans ; 
Gallionellis affinis forme pedicellate, affixe. f 
The only species of this genus is from the Ocean near Callao im 
Peru. It is the only extra European genus which after careful ex: 
amination has retained its peculiarity. 
VILL. Triceratium.—Char. gen. Animal polygastricum e Bacillari- 
orum familia, ejusque Naviculaceorum sectione, liberum, lorica bi: 
valvi triangula (silicea) in utroque latere tridentata vel corniculata 
spontanea divisione longitudinali sub cute multiplicatum. 
Biddulphiam triquetram aut Desmidium siliceum refert. 
Three species of the genus are known, of which two have occurred 
alive in the North Sea, and one only in a fossil state in the chalk 
marls of Greece.” One of the recent species has likewise been found 
fossil in the same chalk marls. Two species are figured on Plate’ 
VEIL 
1X. Triropiscus.—Char. gen. Animal polygastricum e familia Ba- 
