184: 
NOTES AND CORRESPONDENCE. 
On the Structure of Amphora, a genus of Diatomacesz, and the 
Diagnosis of its Species—-When Linnzeus said that all objects 
of natural history must have a specific name, he did not mean 
a trivial name (which was not then invented), but what is called 
a short, distinctive character, otherwise it is not imperative on 
others to adopt the trivial name imposed, or recognise it in any 
way. The want of short characters (intended to place clearly 
before the mind the few essential points of difference between 
supposed new and already known forms or species) cannot be 
supplied by figures or diffuse descriptions of the entire object, 
as these leave quite in the dark the precise marks of dis- 
tinction observed by the writer, if such actually existed. In 
composing either a defining character or a detailed descrip- 
tion, it is also necessary to use the technical language of that 
science. Recently, in referrmg to Dr. Gregory’s paper on 
the Diatomacez of the Clyde, published in the last part of 
the ‘Transactions of the Royal Society of Edinburgh,’ I 
regretted that this patient observer had neglected these 
rules, and thus enveloped his whole memoir in an almost 
impenetrable cloud; thus not only precluding himself from 
claiming any right of priority of names, in the event of 
the same form being afterwards correctly characterised by 
another under a different name, but depriving the paper 
itself of its claims to be considered a scientific one. The 
same unfortunate cloud renders it difficult to understand 
what Dr. Gregory’s actual views of the structure of Am- 
phora are; although, from expressions used by him, he 
appears to enunciate the theory, that what other writers call 
a simple frustule, ought to be considered as a double one. 
To make this more intelligible to those not generally 
interested in such pursuits, I would refer to the structure 
of a diatom, as explained by Smith in his ‘Synopsis of 
British Diatomacee ;’? and recommend the mode of proving, 
by Canada balsam, whether the frustule is single or double. 
When tested in this way, what is commonly called a simple 
frustule is found to be actually so, and of one cell, so 
that Dr. Gregory’s hypothesis is untenable. The struc- 
ture of the genus Amphora appears to have been also 
slightly misunderstood by Kutzing and Smith. The real 
form of the frustule is not a spheroid, as they must have 
considered it, but rather like that of a coffee-bean, rounded 
at the back and hollowed out in front, the line connecting 
