68 MESSES. W. WEST AND Gr. S. WEST ON 



"horizontali papillarum 4 ; a vertice yisse rliomboideo-ellipticse, polls tridenticulatis 

 jiixta margineni lateralem utrumque papillis 4 instructis ; a latere visae depresso- 

 ellipticae, apicibus subtrimcatis, angulis superioribus utrobique papilla singula 

 pryeditis. 

 Long. 19 /I ; lat. 24 n ; lat. isthm. 6*5 ju ; crass. 13*5 ju. 

 No. 1. 



This species comes nearest to Cosmarium pseudotaxichondrum^ Nordst. (Nonnull. Alg. 

 Brasil. p. 20, tab. ii. fig. 5), but is smaller and proportionately broader at the apex ; 

 in front view it has an additional tooth at each side and fonr granules just within 

 the apex ; in vertical view it is more rhomboid, and has the grannies more pronounced 

 and loitliin the margins ; the poles are also trigranulate, and the side view is also 

 very much compressed (not globose), with one papilla on either side of tlie truncate 

 apex. 



107. Cosmarium rostellum, nov. sp. (PL YII. fig. 19.) C. submediocre, circiter 

 1 J-plo longius quam latum, profunde constrictum, sinn angusto-lineari ; semicellulse 

 truncato-pyramidatsB, angulis inferioribns obtuse apiculatis, lateribns leviter 5-6- 

 undulatis, angulis superioribus subrotundatis, apicibus subrectis, in centro granulis 

 5 instructis ; a vertice visse ellipticae, polls subacutis medio utrobique granulis 

 tribus instructis ; a latere visse subrotundatae, medio utrobique granulis binis 

 instructae ; membrana irregulariter punctata 



Long. 46 iu ; lat. 36'5ju; lat. aplc. 21^; lat. isthm. 11 /i; crass. 20/*. 

 No. 0. 



Porma minor. (PL VII. fig. 20.) 



Long. 35 ft ; lat. 29 fx ; lat. apic. 17 n ; lat. isthm. 9 ^ ; crass. 13"5/i. 

 No. 0. 



108. Cosmarium scitum, nov. sp. (PL VII. fig. 29.) C. parvum, paullo longius quam 

 latum, profunde constrictum, sinu angusto-lineari extremo ampliato ; semicellulse 

 truncato-pyramidatse, angulis inferioribus subrotundatis trigranulatis, lateribus sub- 

 rectis subconcavisve, intra apices subconvexos serie granulorum 5-6, granulis paucis 

 sparsis Intra ambitum totum, in centro granulis 5 in seriebus duabus (2 infra et 3 

 supra) ; a vertice visse eUipticse, polls subacutis in medio utrobique granulis tribus 

 instructis, intra marginem lateralem utrumque serie granulorum 5-6, granulis 2-3 

 utrobique prope polos ; a latere visse subsphaericse, apicibus truncatis, in ambitu toto 

 granulis distantibus 6 prsedita? ; pyrenoidibus binis. 



Long. 28-32-5 fx ; lat. 26-29 fi; lat. isthm. 7*5-8 /t ; crass. ll-5-15'5 fx, 



Nos. and 1. 



This comes nearest to C. polymo7'phuni, Nordst.; *patUense, Boerg. (Desm. Brasil. 

 p. 943, tab. iv. fig. 28). It differs in its smooth apex and upper part of its sides, the 

 inferior angles alone being trigranulate ; the granules in the centre are differently 

 arranged, and the vertical view has subacute poles with only three median granules at 



