114 O’MEARA, ON DIATOMACE. 
Campylodiscus simulans, Greg. 
Coscinodiscus concavus, Greg. 
Pf nitidus, Greg. 
Navicula Hennedyi, Greg. 
ig estiva, Donkin. 
a forcipata, Grev. 
55 hyalina, Donkin. 
a nitida, Greg. 
es clavata, Greg. 
re lineata, Donkin. 
» pretexta, Greg. 
maxima, Greg. 
Pinnularia pandura, var. elongata, Greg. 
e semiplena, Grev. 
As regards the forms included in the foregoing list, I have 
no remark to make beyond the record of their occurrence, 
except in the case of Campylodiscus simulans and Coscino- 
discus nitidus. Several frustules of Campylodiscus simulans 
have occurred in the gathering, and in many instances I 
have observed the same peculiarity which Dr. Gregory noticed 
in the frustules of Campylodiscus bicruciatus, namely, that the 
opposite valves are frequently placed at right angles to each 
other. 
Coscinodiscus nitidus is figured and describedby Dr. Gregory 
in his paper on ‘‘ New Forms of Diatomacez found in the 
Frith of Clyde,” and supposed by him to be the same as a 
form previously figured from an imperfect specimen found 
in the Glenshira Sand. In the paper on the Clyde forms 
Dr. Gregory, having described Coscinodiscus nitidus, proceeds 
to say, “ This pretty disc was figured without a name from 
an imperfect specimen in my last paper on the Glenshira 
Sand. (‘Trans. Mic.Soc.’ VolV, Pl. I,fig.50.) Having found 
it tolerably frequent in Lamlash Bay, I now figure a perfect 
example, which, provisionally, I refer to Coscinodiscus.” 
This form found in Lamlash Bay occurs frequently in Dr. 
Wright’s gathering, and with equal frequency is another 
form very like it at first inspection, but which, on closer ex- 
amination, presents distinctive characters. This latter appears 
to me identical with that figured from an imperfect specimen 
in the paper on the Glenshira Sand. A careful comparison 
of many frustules seems to confirm this opinion. The Clyde 
form is accurately described as follows:—*‘ Surface of the dise 
marked with distant and irregularly radiate lines of rather 
large, round, distant cells or granules. The rays are distinctly 
marked towards the mar gin, but somewhat confused towards 
