SOME NORTH AMERICAN DESMIDIE.E. 261 



agreeing well with his figure except in the sinus ; the sinus of our examples was narrow 



as in his description. As his description is too meagre and not quite correct, and also jis 



his figure and description do not agree, we give hoth. 



S. suhmediocre, IJ-plo longius quam latins, profuudc constrictiim, sinu angusto-lineari 

 extremo leviter ampliato ; semicellulye triangulares, anguUs inferiorihus rotundatis 

 et subtruncatis, lateribus inferiorihus inflatis, lateribus superiorilius conaivis, 

 apicibus subtruncato-rotundis ; a vertice visa? triangulares, lateribus concavis, 

 angulis rotundatis ; meml^rana scrolnculata. 

 Long. 42-43 /n ; lat. 28-29 ^u ; lat. apic. 8'5-9-5 ^ ; lat. isthni. 9-10 lu. 

 The membrane is finely scrobiculate, and not "jiunctate granuhite" as stated by Wolle. 



Var, RHOMBOiDEUM, nov. var. (PL XVI. fig. 30.) Var. semicellulis longioribus, lateribus 

 superioribus subrectis, apicibus truncatis efc levissime retusis ; a vertice visis tri- 

 angularibus, lateribus rectis. 



Long. 52 /u ; lat. 27'5 in ; lat. apic. 9*5 ju ; lat. isthm. ll'o ft. 



129. Staurastrum insigne, Lund. Desm. Suec. p. 58, t. 3. fig. 25. 

 Long. 21 /t ; lat. 14 /n ; lat. isthm. 5 /t. 



A smaller and comparatively longer form of this characteristic species was observed. 



130. S. LANCEOLATUM, Arch. in Quart. Journ. Micr. Sc. ii. (1802) p. 218, t. 12. 

 figs. 16-22. 



Var. COMPRESSUM, West, ^""ew Brit. Alg., in Journ. Roy. Micr. Soc. (1894) p. 11, pi. 1. 



fig. 22. 

 Long. 17'5 /t ; lat. 21"2 /i ; lat. isthm. 7'5 /.i. 



131. S. AVERSUM, Lund. Desm. Suec. p. 59, t. 3. fig. 27. 

 Long. 36 ^; lat. 33 ^ ; lat. isthm. 16*5 {jl. 



Ilcib. Orono, Maine. 



132. S. GRANDE, Bulnh. in Hedwigia, vol. ii. (1863) t. 9. fig. 14. 



Var. ROTUNDATUM, nov. var. (PL XVI. fig. 31.) Var. robustum, sinu acutissimo minus 



aperto, semicellulis inflatis, angulis rotuudioribus, dorso convexiore. 

 Long. 81-86 i^\ lat. 67-70 /^; lat. isthm. 20-23 /x. 

 A rather frequent variety. 



133. S. BOTROPHiLUM, Wolle, Desm. U.S. p. 131, pL 42. figs. 11-13. 

 Long. 47 ^ ; lat. 38-40-5 ^ ; lat. isthm. 9 ^. 



The examples seen of this had the apices more al^ruptly truncate tlian WoUe's figure ; 

 the vertical view had slightly refuse sides and less rounded angles. The sinus was 

 narrowly linear. Pig. 13 (Wolle, I. c.) is certainly an incorrect drawing, for it is 

 impossible to get such a wide open sinus from a linear one in any position {vide tig. 11, 

 AVolle, I. c). This approaches *S'. Arnellii, Boldt, in Ofvers. Sv. Vet.-Aliad. Forh. 1885 

 (1886), n. 2, p. 112, t. 5. fig. 21, in form, but has a much narrower isthmus and differently 

 arranged granules. 



SECOND SERIES. — BOTANY, VOL. V. 2 O 



