406 M. E. Hesse on the Pranizze and Ancei. 
few days, he preserved alive in sea-water, instead of putting it 
into spirits. On his return, he found its place occupied by an 
Anceus. From the difference of form, especially in the size 
of the head, he thought that he must have fallen into some 
error; but subsequent observations confirmed his first view of 
the relations existing between the two forms. On the 20th of 
July 1853 he found a Praniza on the fins of a Plaice (Platessa 
vulgaris), which became an Anceus on the 5th of November. On 
the 19th of August 1855, three Pranize were found on the 
body of a red Gurnard (Trigla Pini); these were transformed 
into Ancet on the lst of September. On the 21st of September 
1856, several Pranize were taken on a Gurnard (7. Hirundo), and 
became converted into Ancet on the 8th of October. On the 
10th of June 1857, he found under stones, on a somewhat 
muddy part of the shore, a great number of Pranize intermixed 
with male and female Ancez. In a few days all the Pranize 
underwent their metamorphosis, “so that nothing but Ancez 
remained.” And on the 29th of August 1857, he found 
twenty-one Pranize in the mouth of a Wrasse (Labrus Bergylta), 
which all became transformed into Ance? on the 6th of September 
and following days. 
In all cases, since this period, the Pranize met with by the 
author have undergone the transformation above described, and 
the Ancei thus produced have copulated and produced fertile 
ova, the first products of which were Pranize. ‘The cast skins 
of the Pranize were also found at the bottom of the vessels in 
which they were preserved, and their examination has enabled 
the author to elucidate the structure of the mouth in these 
Crustacea. The facts observed by the author demonstrate that 
the Crustacea hitherto described under the generic names of 
Praniza and Anceus must now be regarded as forming one 
genus, for which the latter name must be retained, as it is only 
in the Anceus-form that they are capable of reproduction. 
Of the general characteristics of the Ance: M. Hesse speaks 
in the following terms :—“ Of all the Crustacea mhabiting our 
coasts, there are certainly none more worthy of attracting the 
attention of naturalists than the Pranize, or rather the Ancez, 
whether we consider the brilliancy and variety of their colora- 
tion, the lightness and elegance of their forms, or the singularity 
of their mode of life ; but, for the present, I shall confine myself 
to speaking of the transformations which they undergo, from 
their escape from the egg until they attain the perfect state. 
When these Crustacea, still in the Praniza-state, are superficially 
examined, we are struck by the resemblance they present to some 
insects of the order Coleoptera, especially of the family Carabidae; 
but this analogy becomes still more striking when they have under- 
