54 MESSES. AV. WEST AND G. S. WEST ON 



55. EuASTRUM cosMARioiDES, nov. sp. (PI. YI. fig. 23.) E. parvum, circiter l^-plo 

 longius quam latum, profunde constrictum, sinu lineari extremo ampliato ; semi- 

 cellulee truncato-pyramidatse, angulis inferioribus late rotundatis, lateribus sub apici- 

 bus retusis, apicibus convexis in medio late emarginatis, angulis superioribus sub- 

 obtusis; a veutice yisse subrhomboidese, angulis latissime rotundatis, lateribus 

 subretusis ; a latere visas subglobosae ; membrana glabra. 

 Long. 25-27 lu ; lat. 18-5-19 n; lat. isthm. 4-5-6 /n; crass. 12-5 u. 

 No. 0. 



This differs from Cosmarium siihlohatmn, Archer, in having the basal angles more widely 

 rounded, in the much sharper superior angles, in the convex emarginate apex (not retuse), 

 and in the different vertical and lateral views. 



Genus Cosm:arium, Corda; Halfs. 



56. Cosmarium submamillatum, nov. sp. (PL VI. fig. 3L.) C. submediocre, IJ-plo 



longius quam latum, profunde constrictum, sinu lineari extremo ampliato ; semi- 

 celhdse truncato-pyramidatse, angulis inferioribus late rotundatis, lateribus concavis 

 infra angulos superiores submamillatos, apicibus truncatis (inter mamillas) ; a vertice 

 visse rhomboideo-ellipticse, mamillis binis intra marginem lateralem utrumque ; a 

 latere visse ovato-truncatse, infra angulos superiores submamillatos leviter concavae ; 

 membrana delicatissime punctata. 



Long. 33-36 ^; lat. 26-29 ^ ; lat. isthm. 55-6-5 n. 



No. 3. 



The four submamillate projections at each apex (two of which are only seen in front 

 view) characterize this species. 



57. Cosmarium granatum, Breb. Liste, p. 26 ; Ralfs, Brit. Desmid. p. 96, tab. 32. fig. 6. 

 Long. 32-42 fx ; lat. 22-27 fx ; lat. isthm. 6-8-5 /x. 



Nos. and 1. 



Forms of this species were seen agreeing with figs 2, 3, and 7 of Borge (Algologiska 

 Kotisa, Bot. Not. 1892, tafl. i.). 



Var. STJBANGULARE, nov. var. (PI. VIII. fig. 4.) Var. minor, Ij-plo longior quam lata, 

 semicellulis angularioribus, lateribus prope basin divergentibus, lateribus superiori- 

 bus levissime concavis, apicibus leviter retusis. 

 Long. 23 fx ; lat. 18 fi ; lat. isthm. 3 ^ ; crass. 9 5 /u. 

 No. 0. 



This variety approaches f. alata, Jacobs., but has the basal angles truncate and not 

 emarginate ; the apex is also somewhat retuse. 



58. Cosmarium in^qualipellicum, nov. sp. (PI. VI. figs. 28, 29.) C. parvum circiter 

 IJ-plo longius quam latius, profunde constrictum, sinu angusto-lineari extremo 



