426 DR. J. E. GRAY ON CYCLANOSTEUS. [May 9, 
of Cycloderma, for he had changed the name again before he pub- 
lished it in the ‘Monatsbericht’ for 1854, p. 216. This work, I 
believe, was not in this country when my catalogue was published ; 
and the paper certainly was not read when my account of the genus 
was printed. Dr. Peters’s type is C. frenatum from the Zambesi. 
It is to be observed that when I quoted Dr. Peters’s MS. in 1852, 
and when he published his characters of the genus under the third 
name in 1854, he simply characterized it as a genus of Trionychide 
with flaps over the feet, and without any bones in the margin of the 
disk. 
When I characterized the genus Cyclanosteus in the ‘ Catalogue 
of the Shield Reptiles in the British Museum,’ I restricted the genus 
to those animals that have nine sternal callosities, as well as a flexible 
boneless margin to the shield. 
In 1856, M. Auguste Duméril, in the ‘ Revue Zoologique’ for that 
year, described a Trionyx that would agree with Dr. Peters’s cha- 
racter of Cycloderma, under the name of Cryptopus aubryi. 
In 1859 I received a Tortoise from the Zambesi, which was sent 
by Dr. Livingstone, with only seven callosities on the sternum. 
Not recognizing it as the one so shortly and imperfectly described 
by Dr. Peters (who does not mention the number of the callosities 
either in his generic or specific characters), and seeing that it was de- 
cidedly different from my genus Cyclanosteus, I described it before 
the Zoological Society, in January 1860, as a new genus, under the 
name of Aspidochelys livingstonit (see P. Z. 8. 1860, p.6). I have 
now no doubt that this is the Cycloderma frenatum of Dr. Peters, as 
they both inhabit the Zambesi, and as Dr. Sclater, who has examined 
the Berlin specimen, informs me they are undoubtedly alike. 
It may be distinct from C. aubryi from the Gaboon ; but these 
Tortoises evidently have an extended distribution in Africa. 
In 1859, in the ‘ Proceedings of the Academy of Natural Sciences 
of Philadelphia,’ Mr. Cope redescribed C. auéryi, and founded on 
it a genus under the name of Heptathyra. This genus is evidently 
synonymous with my genus Aspidochelys, which appeared nearly 
simultaneously. 
In my paper “ On the Trionychide of Asia and Africa” in the 
‘Proceedings of the Society’ for 1864, finding that the Trzonyz with 
nine and the one with seven tubercular callosities had very different 
skulls, and that it was requisite not only to separate them into genera 
but into distinct tribes, and that in my catalogue I had distinctly 
characterized the one with nine under the name of Cyclanosteus, and 
that Mr. Cope had characterized the one with seven, very shortly 
before I had named it Aspidochelys, under the name of Heptathyra, 
while Dr. Peters’s genus Cycloderma applied equally well to both of 
them, I used the two former genera, observing that ‘ the genus Cy- 
cloderma of Peters was constituted to contain the Cryptopus of Du- 
méril, which had a boneless flexible margin to the shield, without 
paying any attention to the number of the callosities, which are also 
coexistent with a very different-shaped skull, and doubtless different 
habits in the animal.” I therefore adopted the genera Cyclanosteus 
