432 M. Serres un Glyptodon ornatus. 



12. Solen brevissimus. 

 S. testa parva, recta, brevi, concolori, cornea ; margo anticus per- 



pendicularis, extus sulco notatus, intus incrassatus ; cardo in utra- 



que valva unidentatus, pone sulcum situs. 

 Long. 37, alt. 9, crass. 8^ mill. 



Singapore. 



The relatively shortest species of Solen I know — distinguished 

 by the perpendicular anterior edge from Ceylonensis, Leach, = 

 intermedins, Phil., and from S. hrevis, Gray, = abbreviatus, Phil., 

 — truncatus, Reeve, Conch. Syst. i. 25. 1, and both from these 

 and from S. versicolor, Phil., by the position of the hinge be- 

 hind the anterior marginal furrow. 



L. — On Glyptodon ornatus. By M. Serres*. 



Recent investigations have made us tolerably well acquainted 

 with the peculiarities of the organization of the Glyptodons; 

 but as regards the number and characteristics of the species 

 little has been done since Nodot, in 1856, summed up the state 

 of science on this point. Unfortunately Dr. Burmeister was 

 unable to consult this work, and consequently his memoir f, 

 although more recent, and notwithstanding the new facts its 

 author was enabled to observe at Buenos Ayi'es, does not con- 

 tribute much to the history of the different species the remains 

 of which have hitherto been discovered. 



The lateral margins of the carapace which forms the subject 

 of this note are alone deficient ; but it is easy to see that upon 

 these margins the osteites of the dermal skeleton, instead of 

 acquiring a tubercular form, as in other species of this group, 

 tended, on the contrary, to become diminished, as in the Arma- 

 dillo. 



The carapace has a semiovoid form, emarginate at the two 

 extremities. Its dimensions are as follows : — 



Distance from the centre of the anterior notch to that of the 

 posterior one 1'14 metre. 



Perimeter of the carapace from one of these points to the 

 other 1-33 m. 



Greatest distance from one lateral margin to the other 0'68 m. 



Corresponding perimeter 1'23 m. 



Aperture of the caudal and cephalic notches, about 0"35 m. 



When this carapace is looked at in profile, one is immediately 

 struck by the complete difference of its aspect from that of the 



* Translated from tlie ' Comptes Rendus de 1' Academic des Sciences,' 

 Oct. 2 & 23, 1865, by W. S. Dallas, F.L.S. 

 t Annals, vol. xiv. p. 81. 



