SOME ]SOETH AMERICAN DESMIDIE.E. 267 



cum annulo granulorum (circ. 8) ad basin semicellularum ; a vertico visae 

 quadrangulares, lateribus concavis, spinis binis bi- vel trifurcatis ornatis, angulis 

 in processus breves profundc trifurcatos productis, denticulis pcrpaucis prope 

 basin. 

 Long. 40-50 /e ; lat. s. proc. circ. 35-38 /i, c. proc. 01-82 /u ; lat. isthm. ll-5-13'5 /u. 

 This at first sight reminds one of S. vestitum, Ralfs, but after examining many 

 specimens, and the characters being found to be quite constant, it cannot be placed 

 under that species, differing from it in its much shorter and almost smooth processes with 

 stoutly trifurcate apices, and in many other characters. This species is constantly 

 quadrangular. 



156. Staurastrum loxgiradiatum, nov. sp. (PI. XVII. fig. 23.) S, mediocre, 2J-plo 

 latius quam longiusfcum processibus), modice constrictuni; semiccUuljr' campanulata?, 

 angulis inferioribus subrotundatis, apicibus truncatis et verrucis emarginatis ornatis, 

 angulls superioribus in processus longos horizontales (vel subdivergentes) et acute 

 nodulosos i^roductis, apicibus processuum bifurcatis; a vertice visae triangulares, 

 corpore parvo, lateribus concavis glabris, angulis in processus longos undulatos 

 productis, intra marginem lateralem unumquemque cum serie verrucarum emargi- 

 natarum 4 ; basi semicellularum trigona. 



Long. 25-30 ^t; lat. c. proc. 67-77 ix; lat. isthm. 6-7"5 /i. 



The nearest species to this is S. Fseudosebaldi, Wille (in Christ. Forh. Vidensk. Selsk. 

 1880 (1881), p. 45, t. 2. fig. 30). 



Porma major. Forma major, apicibus processuum trifurcatis. 

 Lat. 119 n. 



157. S. FLORIFERUM, uov. sp. (PI. XVIII. fig. 1.) S, mediocre, paulo longius quam 

 latius (sine processibus), profunde constrictum ; semicellula) obverse semicirculares, 

 apicibus rectis verrucosis, angulis in processus horizontales longos productis, 

 apicibus processuum tridentatis ; processus nodis dentatis binis, dentibus dorsalibus 

 multo longioribus, ad basin processuum, verruca emarginatti ad latus dorsale et 

 dente ad latus ventrale ; a vertice visie triangulares, lateribus subrectis, angulorum 

 processibus binodulosis productis ad basin dilatatis, intra dilatationes vtM-micis 

 emaririnatis duabus, in centro cum annulo verrucarum tridenticulatarum 6 (duai intra 

 marginem lateralem unumquemque). 



Long. 23-25 /u ; lat. s. proc. 19-21 /*, cum. proc. 53-55 ft ; lat. isthm. 6-5-7'5 /*. 



158. S. Sebaldi, iteinsch, Algenfl. Pranken, p. 175, t. 11. fig. 1. 



As this species is very varial)le, vertical views of two common forms are given. 



Lat. 63-69 ^. (PI. XVIII. figs. 2, 3.) 



Var. ALTUM, nobis. [= S. prohoscideum. Arch., var. altum, Boldt, in Of vers. Sv. Vet.- 



Akacl. Porh. 1885 (1886), n. 2, p. 117, t. 6. fig. 34.] 

 Long. 80 fjL ; lat. c. proc. 70 n ; lat. isthm. 20 n. 



This is too large for S. irroboscideum, and the ornamentation is much nearer that of 

 S, Sebaldi \ it is a common American variety. 



