294 W. AND G. S. WEST 



66 Oscillatoria producta sp. n. (PI. XXV, Figs. 86-90) 



0. trichomatibus sparsis inter alias algas Myxophycearum natantibus, serugineis, 

 subrectis, inter cellulas leviter constrictis, apices versus et juxta leviter attenuatis ; 

 cellulis diametro trichomatis 3-4- plo brevioribus; cytioplasmate granulata, dissepi- 

 menta non granulata ; cellula apicali in processum mamillatum vel digitatum 

 nonnunquam uncinatum, p^us minusve producta, usque diametro 2|-plo longiori, 

 pellucida, ssepe calyptra convexo-conica ornata. 



Crass, trich. 5.3-6.8 n ; long. cell. 1.4-1.8 n. 



Hob. Pond on Mt. Erebus. 



Perhaps the nearest species to 0. producta is the one described as 0. ttoydiana by 

 Gomont (in Bull, Soc. botan. France, xlvi, 1899. p. 39, t. 1, f. 17), from which it is 

 distinguished by its narrower trichomes, the absence of granules at the dissepiments, 

 the differently attenuated apex, and the presence of a calyptra. 



It might also be compared with 0. janthophora Gomont, 0. cortiana Menegh., and 

 0. oJceni Ag , from all of which it is easily distinguished. 



67 Oscillatoria cortiana Menegh. 



1837 ; Gomont in Ann. Sci. Nat. T serie, Bot. xvi, 1892, p. 251, t. 7, f. 17.. 

 Forma cellulis paullo brevioribus; crass, trich. 5.8-6.9 /* ; long. cell. 4-5.5 ju; 

 crass, apic. trich. 2.8-3.3 /u ; long. cell. apic. 7.5-10 ju. 



Hob. Clear Lake, rather scarce among the sheets of Phormidium glaciale. 



68 Oscillatoria priestleyi sp. n. (PI. XXVI, Figs. 99-101) 



0. trichomatibus libere natantibus, densissime aggregatis, pallide serugineis, 

 elongatis et subrectis, apicem versus longe attenuatis, apicibus curvatis et s^pe 

 recurvatis, interdum irregulariter flexuosis, obtusis, inter cellulas non constrictis, 

 hinc inde massa intercellular! inflate- tor ulosa et refringenti interrupts; cellulis 

 subquadratis vel plerumque paullo brevioribus, interdum paullo tumidulis, non 

 elongatis apicem versus ; cytioplasmate minutissime granulatis et interdum cum 

 granulo magno subrefringenti ornato ; cellula apicali obtusa, nunquam capitata ; 

 calyptra nulla. 



Crass, trich. 5-5.9 M ; crass, apic. trich. 2.3-3.2 /x; long. cell. 3-5 n. 



Hob. Lake on west side of McMurdo Sound. 



The only species related to Oscillatoria priestleyi are 0. subitliformis Kiitz., 

 0. cortiana Menegh., and 0. tanganyikce G. S. West, with the first of which it should 

 be very carefully compared. 



0. priestleyi differs from 0. subuliformis in the entire absence of undulation from 

 the straight or gently flexuose filaments, in the much more irregular curvature of 

 their attenuated apices, in the relatively shorter cells, which remain short to the very 

 apex of the filament, and in the presence of numerous refractive lens- shaped masses 

 of deeply coloured and deeply staining intercellular substance. The trichomes are 



