Baur.] -^10 [May 5, 



Not(s on the Classification and Taxonomy of the Testudinata. 



By G. Baur, University of Chicago. 

 (Read before the American Philosophical Society, May 5, 1S03.) 



I. The TypE op Hydtiomedusa tectifera Cope, with General Ob- 

 servations ox THE Genus Hydromedusa and the Classifica- 

 tion OF the Pleurodika. 



Through the kindness of Prof. E. D. Cope, I have received for examina- 

 tion the type specimea of Hydromedusa tectifera Cope. The carapace is 

 totally different from that figured by Boulenger * as Hydromedusa tectifera. 



1. Osteological Differences. — In the diagnosis of Hydromedusa Boulenger 

 states the number of neural bones as seven, and in the figure mentioned 

 seven are shown. In the type specimen there are only six neural bones, 

 allowing pleuralia 7 and 8 to meet in the middle line. The neurals are 

 much more slender than in the specimen figured by Boulenger. The first 

 neural is 39 mm. long and extends to the second pleural, excluding neu- 

 rale 2 from pleurale 1. The first neural measures 6 mm. in front and 15 

 mm. behind. The second neural is only in connection with pleurale 2. 

 The sixth neural bone is placed between the fifth and sixth pleuralia. The 

 pleuralia C do not meet in the middle line, but are separated by the sixth 

 neural and the seventh pleural of the right side, which touches the sixth 

 pleural of the left. The first peripheral (marginal bone) is completely 

 excluded from the second pleural ; it is placed between the nuchal and 

 the second peripheral. Notwithstanding the carapace measures over 

 curve 29 cm. in length, it is not fully ossified ; there are small fontanelles 

 on the side between the pleurals and peripherals and also between the 

 plastron and the peripherals. 



2. Differences in the Dermal Shields. — The first vertebral shield is very 

 much longer than broad (58 mm. : 31 mm.); where it meets tiie posterior 

 cervical shield it is 32 mm. broad ; the breadth of the posterior end of the 

 second cervical shield is 68 mm. There cannot be any doubt that the 

 specimen figured by Boulenger as U. tectifera belongs to a diflerent 

 species from the type. What name it ought to receive I am unable to de- 

 termine. 



Boulenger considers the specimen figured by Waglerf as Hydromedusa 

 maximiliani and that figured by Peters % under the same name as identi- 

 cal species, which he also considers as H. tectifera. 



I'here seems to be no doubt that the specimens figured by Peters and Wag- 



* Boulenger, G. A., Catalogue of the Chelonians, London, 1S89, p. 211. 



+ WaLfler, Job., Natiirliches Si/slrm dcr Amphibien, PI. iii, Fig. 25-42, 1830. 



J Peters, W., " Zur Osteologie dor Ilydromedusa maximiliani," itilll. Arrhiv., 1?39, pp. 280- 

 2^9, PI. xiv. I may mention here that this paper originally api)earod as Peters' Disserta- 

 tio Inauguralis, under the title " Observationes ad Anatomiam Cheloniorum," with one 

 plate (Berolini, 1838). 



