ALG^ FROM CENTRAX, AFRICA. 379 



14. CosMARiuM PECTiNoiDEs Wolle, Desin. U. S. 88, pi. xiv. figs. 

 12-13. Long. 57 /x; lat. 43 /x; lat. isthm. 15 /x; crass. 27 /x 

 (Fig. 9). Mwangadan Eiver, S. of Fulacloga. 



The nearest species to this is C. hinum Nordst. in Wittr. & 

 Nordst. AJfi. E.vsicc. 1880, no. 383, which differs chiefly in its linear 

 sinus, its rectangular basal angles, and its truncate apex. The 

 close resemblance between these two species seems to have escaped 

 the notice of some previous observers who have had occasion to 

 refer to C. biniiui. 



15. C. Mwangadanense, nov. sp. (Fig. 11). C. submediocre, 

 li-plo longius quam latum, profunde constrictum, sinu lineari 

 extremo subampliato ; semicellulre subsemicirculares cum apicibus 

 truncatis, angulis basalibus rotundatis, lateribus leviter biundulatis, 

 elevationibus granulatis, granulis intra marginem subter elevationi- 

 bus, in ceutro cum tumore magno granulorum majorum ; a vertice 

 visie lata) ellipticfe, cum tumore ad medio utrobique. Long. 49 /x ; 

 lat. 41 /x ; lat. isthm. 11*5 /x. Mwangadan River, S. of Fuladoga. 



The isolated patches of granules of this species are very charac- 

 teristic. 



IG. C. suBcosTATUM Nordst. in Wittr. & Nordst. Alrj. et (Edog. 

 in Ital. et Tyrol. 37, taf. xii. fig. 13. 



Forma minor (Fig. 15). Forma minor, crenis lateralibus pauci- 

 oribus. Long. 21-5-23 /x ; lat. 18-19 /x ; lat. isthm. 4-2-4-8 /x ; 

 crass. 11-5 /x. Mwangadan River, S. of Fuladoga. 



17. C. Blyttii Wille, Bidrcuj til Kundsk. om Norges Ferskv. Ahj. 

 25, tab. i. fig. 7. Long. 21 /x ; lat. 19 /x; lat. isthm. 6 /x. G. Las- 

 chan, Leikipia. 



18. C. PUNCTULATUM Breb. var. ornatum Istv. Schaar. Diag. 

 Algar. Nov., Notarisia, 1886, 237. Forma cum granulis radiatim dis- 

 positis. Long. 21 /x ; lat. 18 /x ; lat. isthm. 6 /x. Mwangadan 

 River, S. of Fuladoga. 



19. C. Phaseolus Breb. ; Ralfs, Brit. Desm. 106, tab. 32, fig. 5. 

 Long. 27 ft ; lat. 26 /x ; lat. isthm. 7*5 {jl ; crass. 14-5 /x. Mwanga- 

 dan River, S. of Fuladoga. 



20. C. trochiscum, nov. sp. (Fig. 12). C. parvum, l|-plo 

 longius quam latum, profundissime constrictum, sinu angusto- 

 lineari extremo ampliato ; semicellula3 oblongo-rectangulares, an- 

 gulis leviter rotundatis, angulis superioribus subincrassatis ; a 

 vertice visse ellipticas, tumoribus parvis binis ad medium utrobique ; 

 membrana glabra. Long. 22-5 /x ; lat. 21 /x; lat. isthm. 4*5 /x; 

 crass. 13 /x. Mwangadan River, S. of Fuladoga. 



21. C. rectangulare Grun. in Rabh. Fl. Europ. AUj. iii. 166. 

 C. gotlandicum Wittr. Om Gott. och 01. Sotv. Ahj. 60, t. iv. fig. 14. 



Var. AFRicANUM, n.var. (Fig. 14). Var. semicellulis multe alti- 

 oribus, lateribus inferioribus divergentibus, lateribus superioribus 

 longioribus, apicibus angustioribus, isthmo angustiori. Long. 

 31-35 /x; lat. 24-25 /x; lat. isthm. 6-7*5 /x; crass. 15 /x. Mwanga- 

 dan River, S. of Fuladoga. 



It differs from C. rectangulare Grun. var. Cambrense (Turn.) 



2 c 2 



