SOME NOETH AMERICAN DESM1DIE.E. 2(39 



163. STArnASTRUM Arctiscon, Lund. Desm. Suec. p. 70, t. k fig. 8. {Xanthidimn 

 Arctiscon, Ehrenb.) 



All the American examples we have seen of this species have shorter processes than 



the European ones, and they have at most hut tliree rings of small teeth on each process. 



Var. GLABRUM, nov. var. (PL XVIII. fig. 14.) Var. processibus brevioribus et glabris 



plerumque levissime bi- (vel tri-) undularis, apicibus processuum saepe dentibus 



majoribus. 

 Long. s. proc. 63 ^, c proc. 121 u; lat. s. proc. 16 m, c. proc. 101-111 ,i; lat. isthm. 21 ^. 



164. S. LEPTACANTHUM, Nordst. in Vidensk. Meddel. 1869 (1870), p. 229, t. 1. fig. 46. 

 Var. DODECACANTHITM, nov. var, (PI. XVIII. fig. 6.) Var. semicellulis processibus 6 



serie inferiore et processibus 6 serie superiore, totis brevioribus quam in forma typica. 



Long. c. proc. 81 ^, s. proc. 38*5 ^; lat. c. proc. 71-73 ^, s. proc. 28-29 yu; lat. isthra. 13-5 ^. 



This variety has 6 processes in both the upper and lower series, and thus differs from 

 both the type and var. tetroctocenmi, WoUe (Desm. U.S. p. 151, pi. 51. figs. 29, 30). The 

 vertical view is more triangular than hexagonal. 



165. S. WoLLEANUM, Butler, ex Wolle, Alg. U.S. p. 41, pi. 57. figs. 1, 2. 



Var. KissiMENSE, Wolle (/. c. pi. 59. figs. 1-3). (PL XVIII. fig. 9.) 



Long, c. proc. 113 i.i, s. proc. 65 /i ; lat. c. j^roc. 110 n, s. proc. circ. 48fi ; lat. isthm. 30 /t. 



This variety has two distinct whorls of six processes. Fig. 1, Wolle [1. c. pi. 59), 

 is not a perfect front view ; if this species is " regular hexagonal," what does WoUe's 

 fig. 2 represent ? 



Var. INTERMEDIUM, nov. var. (PL XVIII. fig. 8.) Var. semicellulis processibus 

 longioribus ad basin latioribus, attenuatis, et ad apices distincte emarginatis. 



Long. c. proc. 90 (U, s. proc. 58 n ; lat. c. proc. 92 m, s- P^oc. 40 ^l ; lat. isthm. 28 n. 



This is intermediate between the type and var. kissimeuse, Wolle, with regard to the 

 length of the processes, though the apices are similar to those of the type but more 

 attenuated. 



[Several years before this species was published, we had this variety drawn and 

 described as S. digitatum.'\ 



166. S. xiPHiDiOPHORUM, WoUc, Alg, U.S. p. 44, pi. 57. figs. 21, 22. 



Var. BRACHYACANTHUM, nov. var. (PL XVI II. fig. 7.) Var. semicellulis altioribus, 



spinis brevioribus leviter divergentibus 6, augulis inferioribus nonnunquam spinis 



brevibus convergentibus instructis ; a vertice visis subtrigoDalibus lateribus subrectis, 



aufjulis subrotundatis verruca obtusa et verruca singula utrobique prope angulos 



instructis. 



Long, cum spin. 46-48 m ; long. s. spin. 27-28 /t ; lat. 25-30 /x; lat. isthm. 12-12-5 ^i. 



This is distinguished from the type and var. simplex, Wolle (/. c. pi. 60. fig. 19), by its 



much shorter spines, which are also divergent. The sinus is more open than is 



indicated by Wolle's figures. This Staurastrum is triangular, and at each angle there 



SECOND SERIES. BOTANF, VOL. V. 2 P 



