578 Journal of the Asiatic Society of Bengal. [N.S., XVIII, 
said to be “ prorsum arcte attenuatae, apice acute rotundatae.”’ 
The spear-head shape of the heterocysts has induced us to call 
the new species Cylindrospermum doryphorum, as this character 
seems to be quite constant. The shines aes are 4-8 p long 
and 2-4 » in diameter at their widest par 
The vegetative cells are cylindrical, “dlightly or nee at all 
constricted at the joints, 4-8 » long and 2-4 » wide, the 
length always exceeding the diameter but never, eeidestee 
being more than twice as long as wide. A peripheral zone 
and the dissepiments are hyaline; within the peripheral zone 
there lies a zone containing granules which are more or less 
irregularly aggregated into longitudinal rows, whilst the 
axial portion is either hyaline or very finely granular. 
Resting spores are rather scarce. Where they occur they 
are nearly always single and adjacent to the terminal hetero- 
cyst, but very rarely they occur in pairs, and sometimes they 
are soperatee from the heterocysts by one or a few vegetative 
homogeneous and of a pale bluish green colour, like that of the 
heterocysts ; usually, however, their contents are rather dense- 
y an somewhat coarsely granular. They are clothed with a 
firm, smooth, hyaline membrane, are 8-12» long and 4-6 p 
wide, and always wider than the vegetative cells. 
Th aments are aggregated into cloud-like floating 
colonies of indefinite outline and a verdigris-green colour. 
the — described by Professor Forti Cylindro- 
spermum tropicum, a species found in Ceylon, differs in the fila- 
ments being échiftcioted at the joints, in the ‘heterocysts being 
twice as wide as the vegetative cells and in the spores being 
up to 43 » in length; C. Goetzei has minutely punctate 
ae yellow spores 12-20 p long and 8 » in diameter —~ 
vegetative cells are 3 to 4 times as long as wide, the 
heterocysts are subspherical or oblong and up to 16 » long; 
and the spores reach a length of 30 to 40 »; C. licheniforme, 
the Kuetzingian figure of which reminds one of our species, 
has oblong-ellipsoidal, not pee -headed, heterocysts and its 
spores are 20-30 (—38) » long; C. maius forms a blackish- 
ly exceed those of our gee and its spores are covered 
by a papillate um has flexuous filaments, 
oe a gotehaed heferooyst <3 icacotben brown gre: 
