406 



tenth, in which the diapophysis is suddenly shortened. The metapophysis and anapophysis 

 are distinct in the eleventh dorsal, and continue to the penultimate lumbar. Seven pairs of 

 ribs directly join the sternum, which consists of six bones. The clavicles are complete and 

 strong. The supraspinal fossa is broader than the infraspinal one. The spine of the sca- 

 pula is lofty, but thin. The acromion is long and bifurcate, the anterior division being the 

 longest, and curving towards the clavicle. The coracoid stands out distinctly from the inner 

 side of the neck of the scapula. The deltoid ridge is thick, but not prominent. The hume- 

 rus shows a small perforation between the condyles, and is also perforated above the inner 

 condyle. The bones of the fore-arm admit of free rotatory movements. In the femur there 

 is a rudiment of a third trochanter near the base of the great trochanter. The tibia is not 

 confluent with the fibula. 



Mm. South. 



2255. The skull of a female Marmot (Arctomys Marmotta), with a mutilated occiput. 



It shows the perforation in the short and broad posterior part of the squamosal. The 

 temporal muscles were large, and their ridges meet upon the parietal. The coronoid pro- 

 cesses of the lower jaw have a corresponding development. The interorbital part of the 

 frontals is a broad, sh'ghtly concave platform, sending out a strong postorbital process on each 

 side. The malar bone is long, strong, angular, forming nearly the whole of the zygoma. 

 The antorbital foramen is unusually small : its lower border extends into a tubercle. The 

 nasal bones pass further backwards than the premaxillaries. The bony palate is broad, and 

 extends backwards beyond the molar series : it is terminated by two semicircular notches. 



Mits. Brookes. 



2256. The mutilated skull of a Marmot {Arctomys Marmotta), showing the chief part 

 of the teeth in situ. 



The cavity of the cranium is exposed, and the basisphenoid shows no trace of sella or of 

 clinoid processes. 



Hunterian. 



2257. A mutilated skull of a Marmot {Arctomys), said to be from Valparaiso. 



It agrees in size with the Arctomys Marmotta, but differs in the bony palate becoming 

 narrower behind, and in its posterior notch not being divided by a median projection. The 

 entry to the rhinencephalic chamber is also more contracted. The teeth from the right side 

 of both upper and lower jaws are removed and separately displayed : they are numerically 

 the same as in other species of Arctomys, and have short and wide-set roots. 



Presented by 8. P. Pratt, Esq., F.E.S. 



2258. The cranium, with a mutilated occiput, of a smaller species of. Arctomys, from 

 Valparaiso. 



It has the squamosal perforation, the broad and flat frontal platform, with strong post- 

 orbital processes, the small antorbital foramina, with the external tubercle, and the long and 



