THE FEESllWATER ALGiE OE MADAGASCAK. 45 



lateribus rectis, apicibus triincatis, leyitcr expansis, tuberculis spha^ricis 26 (visis 11) 



mstructis ; membrana punctata. 

 Long. 645 ^i ; lat. ad bas. semicell. 45 /n ; lat juxta apic 41 « 

 No. 0. 



This species differs from Fleurot(enmm orientate [=2)ocidium orientale, \V. JJ. Turn. 

 1. c. p. 31, tab. iv. fig. 1] in wanting the basal inflation, in its straight sides, and 

 in the fewer apical tubercles. 



18. Pleurot^nitjm PAEALLELUM, nov. sp. (PI. Y. fig. 3 k) P. magnum, diametro circiter 

 18-plo longius ; semicellulEe inflatione basali, supra partem basaleni Icvissime uni- 

 undulat«, lateribus rectis et parallelis, apicil)us trunaitis, tuberculis 26 (visis 14) 

 sphaericis parvis intra marginem apicis instructis ; mem])rana irregulariter et minute 

 punctata. 

 Long. 724 ^ ; lat. ad bas. semicell. 48 ^ ; lat. ad apic. 36 fi,. 

 No. 0. 



Tliis differs from P. orientale in the parallel sides, in not having the apices expanded 

 and with fewer tubercles, which are loltldn the margin. It differs from P. monili. 

 ferum (n. 17) va. its apex and basal inflations. 



19. Pleurotjenium fiemum, nov. sp. (PL V. fig. 41.) P. magnum, crassum, diametro 

 circiter 8-plo longius ; semicellulae cum inflatione parv4 basali, lateribus subparallelis, 

 apices versus subito attenuatae, apicibus subtruncatis, tuberculis oblongis parvis 32 

 (visis 17) intra marginem apicis instructis ; mcmbranfi dense scrobiculatA. 



Long. 560 {h ; lat. ad bas. semicell. 75 {h ; lat. ad med. semicell. 73 ^ ; lat. ad apic. 48 \l. 

 No. 0. 



20. PleurottENIUM Ehrenbergii, De Bary, Conj. p. 75. {Bocidium Ehrenbergii, Ualfs, 

 Brit. Desm. p. 157, tab. xxvi. figs. 4 a, b, c.) 



Long. 296-303 joo ; lat. ad bas. semicell. 19-21 jt* ; lat. ad apic. 13*5 /a. 



Nos. and 1. 



Eorma semicellulis plus attenuatis, inflatione basali majore. 



Long. 338 ^ ; lat. ad bas. semiceU. 355 ^i ; lat. ad apic. 17-5 ^. (PL V. fig. 40.) 



No. 22. 



This is similar in form to P. quantillum \_=Docidium quantillum, W. B. Turn. Freshw. 

 Alg. of E. India, p. 28, tab. ii. fig. 9, and tab. iv. fig. 12], but is much larger. 



21. PLEUROT.ENIUM BASITJNDATTJM, nov. sp. (Pi. V. fig. 35.) P. mcdiocrc, elongatum, 



diametro circiter 26-plo longius ; semicellulae vix attenuatae, cum inflatione rotundA 

 magna in basi, et undiilis 4-5 supra scnsim et gradatim minoribus poene medio 

 tenus instructis, apicibus tnmcatis et subincrassatis ; membranu sparsini scrobicu- 

 lato-punctata. 



