757 



pears in the last free lumbar vertebra. Five vertebrae here compose the sacrum, and four 

 others may be traced in the rudiment of the tail. Eight pairs of ribs directly join the ster- 

 num, in which four bones may be distinguished, besides the broad manubrium : to this are 

 articulated the first, second, and half of the third pairs of ribs. The lumbar series forms a 

 straight line with the contiguous half of the dorsal series. 



Hunterian. 



5030. The cranium, vertically and longitudinally bisected, of a young Gibbon 

 (Hylobates}. 



The deciduous molars have not been shed : the first true molar is come into place, and the 

 second has pushed its crown through the alveolar outlet. The canine and the two premolars 

 are exposed, in their formative alveoli, in the left half section. The chief peculiarity of this 

 skull is the backward extension of the frontal to the superoccipital, with which it unites, 

 separating the parietals from each other, as in many fishes, e. g. No. 148. The interparietal 

 portion of the frontal has been a quarter of an inch in breadth. The alisphenoid is perforated 

 by the foramen ovale, and unites with the parietal. The premaxillary does not reach so high 

 as to join the nasal. In the interior of the cranium may be noticed the deep cerebellar fossa 

 in the petrosal, and the extension of the posterior clinoid process forwards to join the anterior 

 one. The lateral sinus terminates in the fossa jugularis. 



Hunterian. 



5031. The skeleton of a Siamang, or Ungka Ape (Hylobates syndactyld). 



This is of an immature animal with the deciduous teeth. The vertebral formula is : 

 7 cervical, 13 dorsal, 4 lumbar, and 8 sacro-caudal. The pelvic extremities are not so long in 

 proportion in this species as in the true Gibbons, and the pectoral extremities are still more 

 remarkable for their length and slendemess. Seven pairs of ribs join the sternum directly, 

 the elements of which have already coalesced into a manubrium and body. The first, second, 

 and half the third pairs of ribs articulate with the manubrium. The superoccipital has 

 coalesced with the left parietal, although the suture between it and the exoccipitals is not yet 

 obliterated. The alisphenoids join the parietals : the premaxillaries do not reach the nasals. 



Mm. Brookes. 



The following, to No. 5049 inclusive, are parts of the same skeleton of an adult male 

 Siamang (Hylobates syndactyla) : 



Presented by George Bennett, Esq., F.L.S. 



5032. The cranium. 



Almost all the sutures of the skull are obliterated ; the border of the orbit is thick and 

 prominent, but the superciliary portions do not meet above the nose. The petrosal is no 

 longer swollen into a cellular bulla, but exhibits a well-marked eustachian process. The 

 ento- and post-glenoid processes are well developed. The foramen ovale pierces the ali- 

 sphenoid. The inner half of the grinding surface of the upper molars, and the outer half of 

 the lower ones, are worn down and deeply stained. 



