Transactions. 107 
Other points arise in the study of these numerous but easily 
passed over creatures. For instance, I am fond of thinking that 
it is only to cloak our laziness and ignorance that we divide and 
sub-divide Creation into orders and genera and species. There 
are always, if not in our own Flora and Fauna, then in some 
other, links between one genus and another ; and, if we only 
knew more, we should readily admit that really there is no such 
thing as “species,” or, rather that what we call a “species” is 
only the outcome at one particular epoch, a climax, of innumer- 
able gradations in forms of being. It is doubly interesting, 
therefore, to be able to fill up an admitted gap in the natural 
sequence. By finding, for the first time in Kirkcudbright, this 
little shell, Valvata cristata, one day amid hosts of Planorbis 
albus on the floating pondweed-leaves, one of these links was 
made clear to me. JV. cristata, not only by internal organisation, 
but by shape of shell, connects most palpably the Genus Planorbis 
with the Genus Valvata. Planorbis has a flat discoid shell, in 
many species perceptibly convex, indeed, on both sides. Compare 
one of them with the commoner Valvata (V. piscinalis) of our 
Fauna, and see the difference. Then note how neatly and 
timeously this tiny cristata comes in to blend the two genera, 
with its shell, as Gwyn Jeffery remarks, “perfectly flat in all 
stages of growth ”—so like a Planorbis albus, and yet so unmis- 
takably a Valvata in texture and colour, and those more subtle 
distinctions which make the real difficulties of science. In the 
same way Physa acuta, a European species, connects our two 
species of Physa, hypnorum and fontinalis ; and another shell, 
which we ought to get in our district, Zonites fulvus is the link 
between the true Zonites and the true Helicidae. I might 
multiply instances of this kind ; but as this is not a lecture upon 
Malacology, I must refrain. My object is merely to suggest the 
direction in which many of us might find plenty of work and 
study on taking up the subject of mollusks and shells. I repeat, 
in conclusion, that, in addition to the healthful pursuit of 
watching and hunting for these strange little creatures, there are 
no obstacles such as expensive tools or accessories of any kind in 
the path of the adventurer. Even time is not so much a desider- 
atum as in almost any other Natural History pursuit. Some 
scores of pill boxes of various sizes, an old mustard tin or two, a 
long stick to which a salmon gaff or a bag-net can be quickly 
fitted, and, I must add, a passion for dabbling in cool, clear- 
