.256 MESSES. W, WEST AND G. S. WEST ON 



106. Staurastrum aristiferum, Ralfs, Brit. Desm. p. 123, t. 21. fig. 2. 



Var. PARALLELUM, nov. var. (PL XYI. fig. 10.) Var. semicellulis apicibus convexis 

 sed retusis in medio, angulis subcapitato-truncatis, spinis parallelis et levissime 

 incurvatis ; a vertice visis triangularibus, lateribns convexis, angulis productis et 

 truncatis. 

 Long. 35 ^ ; lat. s. spin. 31 ^, c. spin. 62-72 ^ ; lat. isthni. 7'5 /x. 



107. ? S. PTEROSPORUM, Lund. Desm. Suec. p. 60, t. 3. fig, 29. 



Long. s. sjiin. 19 /a, c. spin. 27-5 /^ ; lat. s. spin. 17'5 /x, c. spin. 22 jx ; lat. isthm. 7 /x. 



Mab. Scarbro', Maine. 



A Staurastrum was observed exactly agreeing with tbe above species in vertical view. 

 The front view had the angles very slightly produced, but sufficiently so to make the 

 apex appear very slightly concave ; the spines were typical. 



108. S. SUBSCOLOPACINUM, nov. sp. (PL XVI. fig. 11.) S. minutum, tam longum quam 

 latum (sine spinis), profunde constrictum, sinu subsemicirculari, isthmo elongate ; 

 semicellulae lata? cuneatse, apicibus subrectis, angulis productis subcapitatis, spina 

 singula brevi incurvata ad angulum unumquemque; a vertice visse triangulares, 

 lateribus subrectis, angulis productis subcapitatis, spinis curvatis instructse ; mem- 

 brana glabra. 



Long. 17-5-18 u ; lat. s. spin. l7"5-19/>t, c. spin. 25-27 /x ; lat. isthm. 3-5-3-8 />(,. 



This diff'ers from S. scolapacinmn, W. B. Turn. (Ereshw. Alg. of E. India, p. 107, t. 17. 

 fig. 10), in its much smaller size, in the almost straight sides of both front and vertical 

 views, in its relatively smaller body, and in its somewhat curved and inflcxed spines. 



109. S. UNicoRNE, W. B. Turn. Preshw. Alg. of E. India, p. 107, t. 15. fig. 16. 



Var. OBESUM, nov. var. (PI. XVI. fig. 12.) Var. angustior, isthmo longiore ; semi- 

 cellulis in capitulis angulorum sine collis et subtruncatis, spinis multo minoribus 

 rectis convergentibus, dorso altiore ; a vertice visis obesis, lateribus convexioribus. 



Long. 32 ju.; lat. s. spin. 25"5 ^ ; lat. c. spin. 29 /x ; lat. isthm. 6 ^. 



110. S. BACILLARE, Breb. ; Balfs, Brit. Desm. p. 214, t. 35. fig. 21. 

 Long. 20 ju ; lat. c. proc. 21 ^ ; lat. isthm. 6'5 ^. 



A tetraradiate form near var. obesum, Lund. (Desm. Suec. p. 57, t. 3. fig. 24). 



Wolle's figure (Alg. U.S. pi. 57. figs. 5, 6) of this species is certainly a much stouter 

 form than Lundell's var. obesum ; it is very different from the figure of Brebisson in 

 Balfs (/. c). 



111. S. ABRUPTUM, nov. sp. (PL XVI. fig. 13.) S. minutissimum, IJ-plo longius quam 

 latins, profunde constrictum ; semicellulae subellipticse, apicibus subconcavis, angulis 

 leviter productis truncatis ; a vertice visae triangulares, lateribus concavis, angulis 

 truncatis ; membrana glabra. 



j Long. 9-5 ^; lat. 135 jj. ; lat. isthm. 4-5 ^. 

 Una tantum semicellula a nobis visa est. 



