596 DR. R. V. ERLANGER. 
much rougher than that of F. costaria. Fiss. gibberula is 
mostly about a third smaller than F. greca, and can be easily 
recognised, as the part of the shell situated behind the fissure 
is higher than that situated before the slit. The shell has, 
therefore, a hunchbacked shape, whence the Latinname. The 
shell of F. gibberula is nearly quite smooth. 
If the shell of the three species I have just described be 
placed with the aperture downwards, the slit upwards, on a 
table, it can be readily noticed that the shell only touches the 
table at its anterior and posterior end. If, on the contrary, 
the same experiment is made with the shell of F. nubecula 
it will be seen that the rim of the shell touches the table 
in every point of its circumference. F. nubecula is the 
smallest of the Neapolitan species, being generally smaller 
than F. gibberula; occasionally, however, very large specimens 
get nearly as big as those of F. greca. The shell of F. 
nubecula is much flatter than those of the three other species. 
I could state a great many other minor points by which 
the four species I have just described might be distinguished, 
but I think that those I have mentioned will suffice, as they 
afford a good and convenient criterion. The Emarginula 
I examined also belongs to the fauna of the Gulf of Naples, 
but is difficult to obtain. Dr. Kobelt, in Schwanheim, near 
Frankfort-on-the-Main, who had the kindness to determine a 
part of my material, labelled it Emarginula Huzardi, 
Pay. This species is rather scarce here, and I worked on 
specimens which had been preserved in strong spirit by Dr. 
Schiemenz, who kindly placed several of them at my disposal. 
The preservation was quite satisfactory. 
The Puncturella, which like Fiss. maxima is a Chilian 
form, was collected by Chierchia in November, 1882, and was 
less satisfactorily preserved, the gills and epithelium of the 
mantle cavity being somewhat macerated. Fortunately the 
preservation of the kidneys was good. 
B. Haller (13) having given a very fine figure of the shape 
and position of the right kidney of Fissurella costaria I 
thought it superfluous to give another. When the shell has 
