352 Miscellaneous. 
surface of the bony plates of the Placoderms is covered with stellate 
tubercles, that of Dinichthys is only marked with fine granulations, 
with slightly deeper and very irregular furrows. The fins are only 
known from a fragment 6 inches long and 3 or 4 inches broad, 
which probably formed part of a median fin with ossified rays as 
thick as a man’s litle finger. 
Thus, as we pass from the Dipteri of the Devonian to the existing 
Ceratodus Forsteri by means of the Carboniferous Otenodus and the 
Triassic Ceratodus, so Dinichthys binds together Coccosteus, Pterich- 
thys, Astcrolepis, and Lepidosiren, although in both cases we by no 
means possess all the intermediate forms.—Azbl. Univ. June 15, 
1877, Arch. des Sct. p. 195. 
On an Ostracode Crustacean of anew Genus (Acanthopus), met with in 
the deep Waters of the Lake of Geneva. By M. H. Vurner. 
This entomostracan cannot be referred to any type hitherto ob- 
served in fresh water ; it belongs to the marine family Cytheride. 
Like the representatives of that family it possesses only a single pair 
of maxillee, and, on the other hand, three pairs of feet armed with 
strong hooks at their basal articulation (the other freshwater Ostra- 
codes having two pairs of maxille and two pairs of legs). The 
rudimentary postabdomen is reduced to two rounded lobes, each 
bearing two hairs. The antennez also much more resemble the type 
of the Cytheride than that of the Cypride. 
The reproductive apparatus does not present any thing peculiar ; it 
resembles that of the Ostracodes in general. Besides the sexual 
tube there is a receptaculum seminis in the female, and a very com- 
plicated chitinous copulatory apparatus in the male. The vulve 
are placed below the two postabdominal lobes. 
With regard to its mode of life, this crustacean is unable to leave 
the bottom. It does not swim at all; it sometimes creeps, but 
usually buries itself, and thus travels in the mud and organic debris 
by the aid of its feet and antenne. The hairs and segments of the 
feet are driven into the mud, which serves as a support. Thestrong 
hooks of the basal articulation are especially useful, “but give a 
somewhat awkward appearance to the mode of progression. The 
mechanism of this locomotion may be compared to that of a man 
who endeavours to advance upon his knees, aiding himself with his 
toes. 
The two pairs of antenne act in opposite directions; their action 
may be compared to that of the two anterior paws of amole. These 
are the members which enable our crustacean to bury itself in the 
mud. 
With reference to the origin of this organism two suppositions 
may be formed: it may be descended from a marine species intro- 
duced by some means into our lakes ; or it may have for its ancestor 
a freshwater crustacean ; the genus Candona would be that which 
it most resembles, though nevertheless very dissimilar. The field 
of hypotheses remains open upon this point.—B2b/, Univ. Oct. 15, 
1877, Arch. des Set. p. 334. 
