106 BRIGHTWELL, ON THE FILAMENTOUS, 



didymus. This occurs not unfrequently in guano. The horns 

 proceed immediately from apertures on each side of the frus- 

 tules (an essential character of Ehrenberg's genus), and differ 

 in this respect from our newly-discovered species, in which 

 the horns proceed from, or rather are an elongation of the 

 intermediate rings. 



Two species from the Antarctic Sea are briefly described by 

 Ehrenberg ( C. dicliceta and (7. tetrachccta) ; each frustule is 

 smooth, and the horns (of which the former species has two 

 on each side, and the latter four) are very long and filiform. 

 These species were, we believe, found in pancake-ice, and 

 were brought home by Dr. J. D. Hooker. 



Two species from Bermuda earth, marked as doubtful, are 

 described by Dr. Bailey (C. hacillaria and C. diploneiis), 

 and he has also recently described and figured a remarkable 

 species, named by him C. boreale, found in the stomach of 

 Botriodactyla grandis.'^ Tlie horns of this species are very 

 long, and armed with numerous minute spines. Dr. Bailey 

 describes and figures a small species also found in guano, 

 named by him C. incurvum, which we have found plentiful 

 in South American guano. 



Of the allied genus Goniotliecium, eight species are de- 

 scribed by Ehrenberg, all found in the Richmond earth, North 

 America. The two largest and most common are G. Rofjersii 

 and G. odontella, and we think it probable tliese will turn out, 

 if discovered in a recent or living state, to be Chatoceri. Of 

 the remaining six species, we are led to conclude, from the 

 discovery of the Breydon species, that two of them belong to 

 the genus ChcEtoce7'OS, and are, wher». living, filamentous. They 

 are Goniotliecium gastridium, of which we have found many 

 specimens with the horns perfect, and G. crenatwii. A figure 

 of a frustule of this species is given in the Microgeologie of 

 Ehrenberg ; and it can scarcely be distinguished from the 

 frustules of the Breydon species. Similar frustules are of fre- 

 quent occurrence in African and other guano, and in several 

 fossil earths of marine formation, and we have detected recent 

 specimens in a gathering lately sent us from IMonterey Bay, 

 North America. Goniotheciiim hispidum and G. didyniuvi of 

 Ehrenberg, scarcely appear to differ from some of the smaller 

 frustules of the Breydon species. G. navicula and G. barhatiim 

 are marked by Ehrenberg as doubtful species of Goniothecium ; 

 but are clearly allied to G. crenatum, or our Breydon species. 



Several other fossil genera of Ehrenberg contain species 

 which will probably be found to belong to the long-horned 

 filamentous Diatoms. Xauihiojjyxis cingulata has precisely 



* Sec Smithsonian Contributions to Knowledge, Feb. 1854, pp. B, 9. 



