QUARTERLY CHRONICLE. 35 
Professor Claus “ On the Organization of the Cypridine,” 
given in the ‘ Annals and Magazine of Natural History,’ the 
original of which we chronicled last quarter as appearing in 
‘Kolliker’s und Siebold’s Zeitschrift, p. 143. During a 
residence at Messina Professor Claus turned his attention to 
the little Crustacea which swarm in the waters of the sea. 
He was particularly struck by a small Ostracode, of the genus 
Cypridina, in which he detected, even with a low power of 
the microscope, an accessory single eye in addition to the 
large, paired, compound eye, and a heart beating with regular 
pulsations. This latter discovery naturally surprised him, 
as in the other two families of Ostracoda (the Cypride and 
the Cytheride) the heart is entirely deficient. A more atten- 
tive examination of these Crustacea soon showed, however, 
that the Cypridine differ much more from the other Ostra- 
coda than the Cypride and Cytheride from each other. The 
fact that an organ so important as the heart may sometimes 
exist and sometimes be deficient in animals so nearly allied to 
each other is doubtless surprising, but by no means without 
precedent. Thus, it has been demonstrated that the Copepoda 
are in the same case. M. Claus himself has shown that if the 
Cyclopide, Harpactide, and Coryceide are always destitute 
of a heart, the allied Pontellide and Calamide are always 
furnished with one. Moreover, the author is not the only 
person who has observed the heart in the Cypridine, as M. 
Fritz Miller mentions it in a recent work (‘ Fir Darwin,’ 
1864). The sole visual organs hitherto known in the Cypri- 
dine were the paired eyes, in which M. Lilljeborg has detected 
a complication of organization very similar to that of the 
eyes of the Cladocera, although the latter are fused into a 
single mass, forming, as it were, a median eye. Nevertheless, 
traces of a primitive division into two halves in the Side, the 
Lyncei, and the Estheria, enable us to establish unhesitatingly 
the homology of this apparently single eye of the Cladocera 
with the paired eyes of the Cypridine. A further homology 
is presented when we find in the Cypridine, besides the large 
compound eyes, a small, simple, median eye, perfectly similar 
to that which exists, in addition to the compound eye, in the 
Daphnia. The Cypridine present other peculiarities worthy 
of mention. As a general rule, the Ostracoda are characterised 
by the small number of their appendages, as there exist only 
two, or at most three, pairs of locomotive appendages behind 
the gigantic maxille. In fact, the last pair of feet disappears 
completely, and the others are converted into organs of 
manducation. On the other hand, the mandibles are con- 
verted into locomotive appendages. The antennz also serv- 
