30 
As a doubt had arisen as to the distinction of this species from the 
Hemione, Equus Hemionus, of Kutch, I have compared these skulls 
with the skull of the latter belonging to an imperfect skeleton, which 
was kindly presented to the Museum, with the skin, by the Earl of 
Derby, from an animal which lived some time in Knowsley Park. 
The forehead of all the three specimens of #. Kiang is rather con- 
vex between the eyes, and the centre of the face is narrow and keeled 
on the sides; while in the skull of #. Hemionus the forehead is flat 
between the eyes, and the centre line of the face is rather broader and 
rounded gradually off on the sides, and the incisive bone is longer and 
more gradually arched, making the incisor more perpendicular in the 
latter than in any of the former. 
But the most distinctive character between the four skulls is in the 
position of the infraorbital foramen. In F£. Hemionus it is high up, 
about one-third the space between the face-line and the back edge of 
the teeth ; it is far back, being directly over the front end of the cheek- 
ridge and the back edge of the third grinder: while in all the three 
specimens of the skulls of #. Kiang this foramen is lower down, being 
nearly in the centre of the space between the face-line and the base 
of the teeth, and it is placed in a line over the back edge of the second 
grinder, some distance in front of the end of the cheek-ridge. 
The under surface of the body of the posterior sphenoid is narrow 
and convex in E'. Hemionus, and broad and flat in #. Kiang. The 
vomer is much more compressed in the latter than in the £. Hemionus. 
I am not certain that the distinctions here described may be sufli- 
cient to show that these two animals are separate species, but they 
indicate the necessity of the subject being more fully examined. 
In the position of the suborbital foramen the H. Kiang more nearly 
resembles the #. asinus, and the EL. Hemionus that of #. Zebra and 
E. Burchellit. 
Two of the skulls of the #. Kiang show the small rudimentary 
grinder in front of the other ; but this tooth is to be more or less di- 
stinctly observed in the skulls of the other Hquide in the Museum 
collection. I may observe, that in the skull of Equus Burchellii in 
the British Museum collection, this tooth is placed on the imner side 
of the first true grinder. 
3. DESCRIPTION OF THE ANIMAL OF TRIGONIA, FROM ACTUAL 
pissEcTION. By G. Huxuey, Ese., R.N., wiTH AN INTRO- 
DUCTORY NOTE BY Proressor KE. Forsss, F.R.S. Etc. etc. 
(Mollusca, Pl. ITT.) 
The accompanying account of the animal of Trigonia was forwarded 
to me by Mr. Iuxley, Assistant-Surgeon to the Rattlesnake, now sur- 
veying in the Eastern and Australian Seas, under the able command 
and scientific zeal of Capt. Owen Stanley. 
The great number, beauty and geological importance of the species 
of this interesting genus have made especially valuable a knowledge 
of the structure of its animal. Quoy and Gaimard were the first to 
give any account of it, and a figure and description of the animal of 
