214 THE AMERICAN MONTHLY [September, 



C. A. Agardh founded the genus Homa:ocladia in 1S30, and 

 gives two species, H. Martiana^ locality, Venice, and H. Ati- 

 glica^ locality, Plymouth ; and F. T. Kiitzing describes six spe- 

 cies, H. pumila =Schizone7na pinnila^ C. A. Agardh, locality, 

 the Adriatic ; H. inojiiliforjnis^ F. T. K., 1S44, locality, Trieste ; 

 H. Anglica., C. A. A., locality, Plymouth ; H. Martia?ia., C. A. 

 A., 1S27, locality, Venice; H. arbusaila^ F. T. K., 1844, local- 

 ity, Venice, and H. dilatata, F. T. K., 1S44. L. Rabenhorst in 

 Flor. Eur. Alg., 1864, gives U. Martiana^ C. A. A., b. afiglica^ 

 C. A.A.,c. Arbusczila^Y.T. K. ,d. <///«/«/«, F.T. K.,e. monili- 

 fo7-7nis,Y . T. K., H. Jiliformis^y^ . S.^h. J~or7na parva^ . S., H. 

 BiihiheiDiiana^ L. B. (Alg. N., 1301), //. pu7)iila^ C. A. A., 

 H. petiicilata^ F. T. K., 1S49 (^P- ^••> P''^g^ 97) ' ^- lub7-ica^ F. 

 T. K., 1S49 (Sp. AL, page 98), which are the " Frustnla recta," 

 and H. sigJ7ioidea^ W. S., and H. Vidovichii^ A. G., 1862 

 (Wien, Ve7-h.^ P^ge 586, tab. xii, fig. 32), which are the "■ Frus- 

 tula sigmoidea." 



Now all these species, with the exception of Ba77gia 7/iica7is^ 

 C. H. L , are one, and, as the formation of a frond or tube is not 

 generic, they are but one sjDecies of the genus Nitzschia^ A. H. 

 H., 1845 (Brit. Fr. Alg.). But I think they can be with reason 

 referred to Sigmatella, F. T. K., 1833 (Alg. Dec). As to the 

 specific name, Ma7-tia7ia^ C. A. A., is the oldest, and must stand. 



I have H. Ma7-tia77.a from Beaufort, S. C, where I gathered 

 it. It grows on oysters ( Oi'/rea Vi7g/7zica) , and I have //. Sig- 

 ?7ioidea from E. Newark, N. J., Aug., 1S89, Sept., 1S89 ; Harri- 

 son, N. J., July, 1S90 ; Waverly, N. J. (fresh water) , Aug., 1890, 

 a stream running down by Mt. Pleasant Cemetery, Newark, N. 

 J. (fresh water), Sept., 1890; head of the same stream near 

 Belleville avenue, Newark, N. J., Sept., 1890, and in the Passaic 

 river (salt water), vSept., 1890, and in the same place Aug., 1891. 



Now as to the genus. I have already given the reason for not 

 accepting Ho7)iccocladia. And as W. Smith says, "• tlie structure 

 of the frustule, which is that of the genus Nitzschia" it cannot 

 be classed as a sepai'ate genus on account of the presence of a 

 frond or tube ; and, as I have said, I prefer to class it as Sigtna- 

 tella^ F. T. K. As to the species, Raphadoglcea medusina^ F. 

 T. K., is with short frustules ; R. nia7iipiilata^ F. T. K., is with 

 long and also short frustules ; R. i7ite7'7-upta^ F. T. K., with short 

 frustules ; Homceocladia pzutiila^ F. T. K., with short frustules ; 

 H. 7no7iifo/-7)iis, F. T. K., with very long frustules ; H. a7iglica, 

 C. A. A., and H. Martia7ia^ C. A. A., with very long frustules, and 

 H. arl)7isc7ila, F. T, K., and H. dilatata^ F. T. K., also with 

 long frustules. In the gathering at Harrison, N. J., I have the 

 long and short frustules in the same tube, showing that they are 

 the same species. The lai-ge form seems to be the sporangium 

 and the small one the normal. But this must be proved by 

 watching the process of conjugation, which has not as yet been 

 seen. And, now, as to the species. I have shown that para- 



