Sketch of the Infusoria of the family Bacillaria. 321 



Art. V. — Sketch of the Infusoria of the family Bacillaria ; by 

 J. W. Bailey, Professor of Chemistry, &c. in the U. S. Mili- 

 tary Academy. 



Part III. 



The animalcules which form the subject of this part of my 

 sketch of American Bacillaria, belong to the sections Echinellea 

 and Lacernata. 



The section Echinellea contains those Bacillaria which diVe fixed, 

 that is, attached either by their extremities, or by a pedicel, to 

 other bodies. They are all siliceous. 



The section Lacernata includes those which have a double 

 covering. They consist of groups of siliceous individuals, sur- 

 rounded by a common gelatinous mass, or enveloped by a mem- 

 branous tube. 



As- many species of each of these sections are often found spon- 

 taneously or accidentally separated from their pedicels or tubes, 

 there is great chance of mistaking them for species of JNavicula- 

 cea. 



Sect. III. ECHINELLEA. 



ISTHMIA. 



Fixed by one end, carapace or lorica siliceous, simple, broader 

 than long, catenate by imperfect spontaneous division, individuals 

 m,aking various angles with each other, and connected by a nar- 

 row isthmus or neck-like process. 



Two species of this genus have been detected, viz. /. enervis, 

 and /. obliquata. Neither of these have, to my knowledge, yet 

 been detected in the United States ; but as the latter is a pelagic 

 species which has been found in places so different and distant 

 from each other as Iceland, England, the Canary Islands, Cape 

 of Good Hope, &c. there can be httle doubt that it will yet be 

 found growing on some of our marine Algas. The first specimen 

 which I ever saw, I detected on a dry specimen of Odonthalia 

 dentata from Iceland. I have since received fine English speci- 

 mens from E. J. Q.uekett, Esq. of London. Few microscopic 

 objects exceed in beauty these little gems of the ocean. I have 

 proved that their carapace is siliceous by the proper chemical 



Vol. xLiii, No.2.— July-Sept- 1842. 41 



