1905] Cushman, Desmid Flora of New Hampshire 259 
retuse apex, with the retuse portion without granules. Length 154- 
1708: breadth 86-93p: isthmus 30-36. Pudding Pond, North 
Conway, scarce ! 
XANTHIDIUM Ehrenb. 
X. ARMATUM (Bréb.) Rab. North Woodstock ! 
Var. CERVICORNIS W. &. G. S. West. Length with spines 166 p: 
without spines 130 p: breadth with spines 125 y: without spines 9o 
p: isthmus 314. Pudding Pond, North Conway! Saco Lake 
(Wood). There was no central group of granules as is frequently 
found in this species. 
X. CRISTATUM Bréb. Length with spines 75: breadth with 
spines 50: isthmus14,. Pudding Pond, North Conway! Noone’s 
Station ! 
Var. UNCINATUM Bréb. Length with spines 80: without 59 P: 
breadth with spines 56 p: without gop: isthmus 11. Pudding 
Pond, North Conway ! 
* Forma ANGULATUM West. Length with spines 72 p, without 54 
PB: breadth with spines 60 p: without 4op: isthmus 114. No cen- 
tral protuberance present. Pudding Pond, North Conway ! 
X. ANTILOPAEUM (Bréb.) Kütz. Length with spines 105 œ, with- 
out 714: breadth with spines 102 y, without 59: isthmus 16 y. 
Pudding Pond, North Conway ! 
Var. POLYMAZUM Nordst. Length with spines 62-84 yq, without 
46-68 u: breadth with spines 58-63 p, without 45-62 4: isthmus 
14-16 p. Pudding Pond, North Conway, frequent!  Intervale ! 
North Woodstock ! 
There is a considerable amount of variation even in this variety. 
Specimens from North Conway and Intervale have the long outwardly 
curved spines, and there are almost invariably but six granules in 
the chain. A considerably different form was met with from North 
Woodstock. This is like the specimen figured by L. N. Johnson 
under the variety Minneapoliense with the exception of the central 
spine. His specimen had the central spine above the chain of gran- 
ules. That form was called var. Johnsoni by W. & G. S. West in a 
. later paper, although Johnson calls attention to the extreme variability 
of this form. ‘The present form lacks the spine of Minneapoliense 
but has the median lateral spine as well marked as the two adjacent 
