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Variabilily.
Relationship.
Synonymi/.
Remarks: — As is seen from the description given above. this species is distinguished,
contrary to most other forms of this sub-familv that are dealt with in this treatise, by the
faet that several organs, especially the first antenna and the sixth and seventh lirnbs, are subject
to a not inconsiderable variation. In spite of this it seems to be very probable that we are
dealing with a single classificatory unit. In any case the striking continuity shown by the
variation, in spite of the limited material, supports this view.
How is this form related to G. W. Müller’s previously described Pacific species
of this genus?
G. W. MÜLLER’s description of G. Agassizi (1895) is rather incomplete. In spite of
that I believe that one may say with pretty great certainty that the Atlantic form described
above by me is a new species, well differentiated from G. Agassizi, which was in reality
already to be assumed a priori on account of the faet that the two forms were caught in
two districts fairly well separated from a zoological point of view.
The characters in which G. Agassizi is differentiated from the Atlantic species are
as follows:
The length of the shell is greater(G. W. MÜLLER, [1895] gives 23mm., 1912 only21 mm.).
First antenna: This has only seven joints. „Das letzte Glied, an dem sich Reste
einer Verschmelzung aus 7 und 8 nicht nachweisen lassen . . . .“ In the male the five
proximal filaments on the b-bristle and the two proximal filaments on the c-bristle are
modified for seizing the female.
Second antenna: The exopodite has no basal spines on the third to the ninth
joints; the second joint on the female endopodite has no bristles; the bristle of the end
joint of the last-mentioned branch does not attain the length of the endopodite.
The seventh limb has more than 200 cleaning bristles on each side.
In all these characters the Atlantic form seems to be more primitive than the Pacific
form. — To judge from G. W. Müller’s drawings the two forms seem to be differentiated
in still more characters. The superficiality of the drawings makes it rather probable, however,
that these differences are due, at least in part, to lack of exactitude on the part of the autlior;
on account of this I have thought it best not to discuss these characters at any length here.
In a later work (1906 b) G. W. MÜLLER mentions (p. 135) that about ten, mostly
young, specimens of this genus — „Alle gehören, soweit ich das feststellen konnte, zu
Gigantocypris Agassiziiu — were caught by S/S „V a 1 d i v i a“* between lat. 14° N. and
lat. 42° S. in the Atlantic and Indian Oceans. Only two pictures of habitus were given.
Whether any of these finds are to be referred to my above described species it is impossible to
decide. It may, however, be pointed out that fig. 5, pi. V shows a type of shell so different
from the one that is characteristic of my species that an assumption of this sort seems anything
but probable. — It may be stated in passing that this figure also suggests most decidedly that
G. W. Müller’s identification with G. Agassizi is incorrect.
It is true that the material of the „V a 1 d i v i a“ expedition was subjected later on
to a renewed investigation by L. LÜDERS (1909), but this author’s drawings of the limbs, etc.
* See also C, Ciiun, 1900, p. 515.
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