321 
Amphora ovalis. Navicula bacillum. 
Cocconeis pediculus. oa cocconeiformis. 
Cocconema lanceolatum. if gibberula. 
Cyclotella antiqua. 35 firma. 
Cymbella cuspidata. i Kotzchii. 
ne Ehrenbergii. Bs minutissima. 
Pe helvetica. =r semen. 
» maculata. * seminulum. 
Cymatopleura solea. Odoutidium parasiticum. 
of elliptica. Pinnularia acuta. 
Epithemia argus. . borealis. 
Fr gibba. 5 divergens. 
i granulata. “ major. 
Ds Hyndmanni. + mesolepta. 
33 sorex. es viridis. 
tA turgida. Pleurosigma attenuatum. 
es zebra. Stauroneis acuta. 
Himantidium arcus. PP pheenicenteron. 
rm bidens. as punctata. 
Gomphonema acuminatum. Surirella nobilis. 
fe constrictum. es elegans. 
a geminatum. 
Particular attention was directed to a species of Orthosira 
which occurred not unfrequently. It was like Orthosira arenaria 
(Moore), with this difference, that the striation in the side view is 
marginal, whereas in the case of Orthosira arenaria it runs from 
the circumference to the centre. The form indicated bears a 
strong resemblance to that figured by Ehrenberg (‘ Mic.,’), as 
Gallionella varians, t. xii, fig. 29; also to another form, 
Gallionella punctigera, t. xv, B, fig. 5; t. xii, fig. 9,h, 7 In 
the latter the striation on the side view is not continued to the 
centre, but is much broader than in any specimen as yet found 
in the Dromore earth. Mr. O’Meara was disposed to regard 
the form as probably a variety of Orthosira arenaria. 
Mr. Archer exhibited two examples of the conjugated state of 
the common diatom Stauroneis phanicenteron, one showing the 
two new frustules in the fully-formed condition, once before 
exhibited to the Club (‘ Quart. Journ. of Micr. Science,’ vol. viii, 
n.s., p. 189), the other in the very earliest stage, or rather just 
immediately after conjugation having been effected. On the former 
oceasion on which he had seen this form conjugated only one new 
young frustule presented itself, and he had thought that so far 
this might be peculiar; in the present instance, however, there 
were two, so that in the former instance one must have been 
accidentally removed in the treatment or otherwise. As before, 
however, the two young fully-formed frustules of the new cycle 
were similar to the parent form, except in being twice their linear 
dimensions, bearing, however, at their apices the “ caps’ formed 
by the remains of the primary envelope borne aloft. The other 
example now exhibited presented the two globular “zygospores,” 
each with a thin coat or wall and greenish-yellow contents. These 
coats were evidently destined to be stretched and rent by the 
