1865.] DR. J. E. GRAY ON CYCLANOSTEUS. 425 
a. equilifera.—The sternal callosities moderately far apart ; front 
gular square; second pair and hinder ones forming a circular disk ; 
abdominal moderate ; posterior absent. 
b. normalis.—The sternal callosities moderate, far apart; the 
gular broad, transverse ; the abdominal well developed ; the posterior 
pair, at first small, at length becoming oblong-elongated, covering the 
bone. 
ce. callosa.—The sternal callosities very large, and almost entirely 
covering the sternum, with some additional, irregular, non-symme- 
trical callosities on the sides of the gular ones; the posterior callo- 
sities very large, elongate-trigonal. 
Dr. Peters is of opinion that in my former paper on Trionychide 
(P. Z. S. 1864, p. 76) I ought to have used the generic name ot 
Cycloderma instead of Mr. Cope’s term Heptathyra. To this I 
reply that I always wish to give every zoologist, whatever may be 
his country, his due, and to use the generic name which, after exa- 
mination and comparison, appears to have priority ; and I am always 
ready to give up my own name for a genus when any other has 
claims to priority over it. Indeed, in this as in other affairs of life, 
the best rule is to do unto others as you would they should do unto 
you. If TI fail in this, it is from error of judgment, and not from 
design. 
In this special instance I do not think there is any ground for 
complaint ; and no objection could have been made, if I had not com- 
mitted an injustice to myself in my anxiety to do what I believed 
was a kindness to Dr. Peters. 
In 1850, having received a Trionyx from the Gambia, I formed 
it into a genus, which I characterized. But recollecting, before I 
sent the MS. to press, that Dr, Peters, in one of his letters to me, 
had stated that he had a Trionyx from Africa, which he shortly de- 
scribed, and on which, he said, he had formed a genus in his MS. 
under the name of Cyclanorbis, when I read my account of this 
Tortoise before the Zoological Society, in November 1852 (see P. Z.S. 
1852, p. 135), I erased my own name and well-defined characters 
and adopted the name of Dr. Peters, giving an extract from his letter 
as the character of the genus, and called the Tortoise Cyclanorbis 
petersit in honour of Dr. W. Peters. 
Dr. Peters subsequently informed me that he had changed the 
name of the genus Cyclanorbis to Cyclanosteus; so in the ‘ Catalogue 
of Shield Reptiles in the British Museum,’ which was published in 
1855, but which was printed many months before it appeared, as it 
had to wait to have the plates finished, I adopted his new name, 
taking my generic characters from the Gambian specimen, which I 
had named petersit, and, referring to Dr. Peters’s MS. notes on his 
species from Mozambique, which I had not seen, quoted it as a 
second species; so that petersii is doubtless the type of the genus 
Cyclanosteus as published in that catalogue. 
Some time after the publication of this work I discovered that 
Dr. Peters had very briefly characterized the genus under the name 
Proc. Zoou. Soc.—1865, No. XXVIII. 
