Dr. H. Burmeister on Giyptodon and its Allies, 303 



I. Glyptodon. 



Tail elongated, conical, the rings before the apex formed of 

 flat shields or scales, the apex more or less cylindrical, with a 

 bulbous swelling at its commencement. Mesocervical bone with 

 five united vertebrse. 



A. Scales or shields of the carapace with uniform warty sculp- 



ture, only the marginal row of the carapace before the mar- 

 ginal tubercles with an elliptical rosette. 



1. G. tuhei-culatus, Owen, Nodot. 



2. G. verrucosus, Nodot (G. tuberculalus, nob., in former com- 

 munication). 



B. Scales or shields of the carapace with a central subhexagonal 



rosette, and six smaller subpentagonal ones on the circum- 

 ference ; the scales of the margin of the carapace before the 

 marginal tubercles with a very large central rosette, occu- 

 pying nearly the whole shield. 

 3 & 4. G. clavipes auctorum. 



Note. — We have in the Museum two different kinds of tails, — 

 the one shorter, broader, and flatter, with an elUptical transverse 

 section ; the other longer, thinner, and higher, with a more cir- 

 cular section. I believe they belong to two different species ; 

 but as I do not know the exact form of the tail of Professor 

 Owen's G. clavipes, I must leave it doubtful which of my species 

 is the true clavipes. 



II. HoPLOPHORUs, Lund. 



Schistopleurum, Nodot. 



Tail short, conical, with six rings of large conical tubercles on 

 the end of each ring of the upper side of the tail*. Mesocervi- 

 cal bone consisting of four united vertebrse, the sixth free. Scales 

 of the carapace with one hexagonal figure in the centre, and six 

 pentagonal ones on the circumference. 



5. H. elongatus, nob. {Schistopleurum typus, Nodot). 

 G. H. gemmatus, nob. [S. yemmatum, Nodot). 



7. H. asper, nob. (G. sjnnicaudus, nob. antea). 



8. H. pumilio, nob., Auales del Museo publico de Buenos 

 Aires, i. p. 77. Of this last species I know only the lower jaw, 

 but, from its general figure, I suppose the species to belong to 

 this section. 



* As we have in the Museum a well-preserved tail of the species which 

 has been described by Nodot as S, typus, with moveable central tubercles 

 on the rings, I can affirm that this construction is not natural, but caused 

 by the imperfect healing of the broken tubercles during the life of the 

 animal. This process is denominated in surgery artificial articulation. 



