Chap. III. GENERA OF CINOSTERNOID.E. 427 



was first described by Sj^ix, but under two distinct names. As I have pos.sessed 

 for a long time several living specimens of the species found in Mexico, and of that 

 of Surinam, sent nie by Prof Baird and Mr. C. J. Hcring, and compared specimens 

 of the third, I can vouch for the accuracy of the distinctions traced by M. LeConte. 

 II. Thykosternum, Ar/. The jaws are strong, and well fitted for cutting, but not 

 for crushing. The head is not as broad as in Cinosternum ; it arches back of 

 the eyes, but is not as wide spread as in Cinosternum, and its sides between 

 the eyes and ears are gently curved outward, and have no such sharp angle as 

 in that genus ; it is high over the mouth, and its roof there is broad between 

 the eyes, so that the orbits open sidewise and forward, not upward. The nose 

 is long and high ; its roof reaches as far forward as the jaw reaches under it, and 

 its sides approach each other downward very fast. The mouth is long and narrow ; 

 the outer surface of the jaws curves outward luider the eye, and then again turns 

 sharply in to the alveolar edge; and further forward also, under the sides of the 

 nose, it curves far inward, but at the symphysis the jaw is drawn down to a 

 short chisel-edge, and its front surface slants back but little. The vertical alve- 

 olar surface is high all round, but especially so at the front end, where it projects 

 downward, and where also it is often raised high up under the nose. The horizontal 

 alveolar surface is broad at the symphysis, and narrowest on each side of it, and 

 widens thence backward ; Init it is not nearly as broad as in Cinosternum. The 

 lower jaw is strong. It gets its strength, not by its thicknes.«, as in Cino.sternum, 

 but l)y its height. It is very high all round ; sometimes it is drawn far up at 

 the symphysis to a long, slender point. The outer surface at the sides is nearly 

 vertical for some distance below the edge. The alveolar surface of the lower 

 jaw is much narrower than in Cinosternum, except at the symphysis, where it is 

 nearly vertical ; near the angle it is almost horizontal, but its outer edge rises 

 somewhat. The cutting edges of this jaw pass close within those of the upper 



based, and agree with him ;is to tlie validity of these the two species of Spix as distinct ; I believe, with 



species. I have only a few objections to his nonun- Wagler, (Syst. Araph. \^. 137,) tliat tliey are the male 



clature. His Cin. mexicaniini is identical with Bell's and female of the same species. Cinosternum cruen- 



Cin.shavianum. Bell's description (Zool.Journ. vol. 2, tatum (Dum. and Bibr., Arch. Mus. 1852, vol. 6, p. 



p. 302) is based upon the identical specimen figured by 238, pi. 16) belongs also to this genus ; but, as I had 



Shaw, from the Leverian Museum, and agrees in every no opportunity of comparing it with the three others, 



respect with those described by Maj. LeConte, who I am unable to say whether it is a distinct species or 



indeed refers to the same figure of Shaw, also quoted not. We have thus at least three distinct species of 



by Bell. (Shaw, Gen. Zool. vol. 3, p. 61, pi. 15, erro- Cinosternum proper: Cin. scorpioides, WagL, (Tes- 



ncouslyrefeiTcdtoStaurotypustriporcatusby'Wagler.) tudo scorpioides, Lin.,) Cin. shavianum, Bell, (Cin. 



The name Cin. niexicanum, therefore, must be given niexicanura, LeC.,) and Cin. longicaudatum, Spijc, 



up. As to Cin. longicaudatum and brevicaudatuui, I (including his brevicaudatum.) and perhaps a fourth, 



disagree with LeConte in one respect, — he considers \' Cin. crueutatum, Bum. and Bibr. 



