268 HAY—EXISTING GENERA OF THE TRIONYCHIDA. [Oct: 2, 
ON THE EXISTING GENERA OF THE TRIONYCHID#/i. 
BY ‘Go cP. ELAW. 
(Read October 2, 1903.) 
This subject was discussed in an interesting and instructive man- 
ner by Dr. George Baur in the PROCEEDINGS OF THE AMERICAN 
PHILOSOPHICAL SociETy, Vol. xxxi, p. 221, 1893. However, the 
present writer, on investigating the subject, has not been able to 
agree with Dr. Baur in all his conclusions, disagreeing with him 
partly regarding the types of some of the genera which he adopts, 
but especially on the value of some of these genera. 
Dr. Baur was undoubtedly correct when he pointed out that the 
current employment of the name Zrconyx for the majority of the 
living Trionychide is not justified, and that the genus has for its 
type Zestudo granosa Schoepff, called Zrionyx punctata by Baur, 
but recorded by Boulenger in his Catalogue of the Chelonians, 
p. 269, as Emyda granosa. ‘This is in agreement with the views of 
Agassiz (Cont. Nat. Hist, U. S., Vol. i, p. 395), who severely con- 
demns the use of the name myda in this connection. Geoffroy’s — 
genus Zrionyx was divided by Wagler in 1830. TZ7ionyx was 
retained for Zestudo granosa, while for most of the other species 
then known the new name Asfidonectes was adopted. The names 
of the species included under it are found in the second column of 
the table on opposite page. No type was indicated for the genus. 
In 1831, Dr. J. E. Gray, in Appendix to Vol. ix of Griffith's 
Cuvier’s Animal Kingdom, pp. 18, 19, and again in his Synopsis 
Repiilium, p. 49, applied the name Zmyda (preoccupied) in place 
of Wagler’s Zrionyx, and Trionyx in place of Wagler’s Aspidonectes. 
It is not necessary to add anything here to what Agassiz and Baur 
have said regarding this procedure, nor to do more than refer to 
Duméril and Bibron’s proposal of the terms Gymmopus and Cryptopus 
to replace Aspidonectes and Trionyx respectively. 
In 1836, Fitzinger (2utwurf Syst. Anordnung Schildkr., pp. 119, 
120, 127) further subdivided the species of soft-shelled tortoises. 
He made use of five sections, and these have since been em- 
ployed as genera. These are Z7rionyx, Aspidonectes, Platypelits, 
Pelodiscus and Amyda. The species enumerated under each of 
these are shown in’ the table already referred to. No types were 
indicated, but granosa was the only one named under Z7onyx, 
