64 Annals of the Carnegie Museum. 



The frontal bone extends far backward, while the occipital is shut 

 out from view in this aspect of the skull in these two monkeys. The 

 marmosets have the temporal ridges also but very faintly indicated; 

 the parietal foramina absent, and the form of the skull much elongated 

 in some individuals, shorter in others. 



Theie is little demanding special description in the cranial cavity 

 of these monkeys which is not already known to anatomists. The 

 'sella turcica' is well marked, with its posterior clinoid process, and 

 the usual foramina exist foi the entrance and exit of vessels and nerves. 

 The tentorium is not ossified in Lasiopyga, though the cerebellar 

 fossae are fairly well differentiated. 



Upon basal view these skulls are all interesting when studied in con- 

 nection with an average human skull viewed in the same manner. In 

 Lasiopyga callitrichus and L. griseoviridis the characters are much 

 alike, while very decided differences are found to exist when we come 

 to compare these with the corresponding characters in the skull of 

 Callith ix jacchns. In the latter the auditory bullae occupy much of 

 the space, being large and elongated, and directed forwards and in- 

 wards to a point about the middle of the cranial base, where their 

 apices are separated by a distance of several millimeters. For the 

 rest, the surfaces are singularly smooth; the sutures nearly obliterated; 

 the pterygoidal plates of the sphenoid prominent, with the hamular 

 processes conspicuous; two very distinct and circumscribed foramina 

 are present upon either side, one just external to either condyle, and 

 the other somewhat larger, immediately external to the anterior apex 

 of either auditory bulla. The palatal roof is short antero-posteriorly, 

 with the sutures nearly obliterated. The plane of the occiput and 

 foramen magnum makes an angle of about 45° with the basis cranii. 



In Lasiopyga the anterior palatine fossa is mesially and longi- 

 tudinally divided by the vomer (Pis. XIV and XV, figs. 5-8). The 

 palate is twice as long as it is wide, and markedly concave from side 

 to side. Traces of the sutures between the bones are persistent until 

 late in life. The posterior palatal grooves are very deep in L. calli- 

 trichus, the foramen occupying its usual site posteriorly. 



ages, representing all the known races of the world, both recent and prehistoric. 

 The opportunity to study them is due to the kindness of Dr. Ales Hrdlicka, Curator 

 of the Division of Physical Anthropology, the work having been undertaken for a 

 certain purpose. It is more than likely that I may now meet with human skulls 

 in which the parietal foramina will be found to be absent, as many of these skulls 

 appear to reveal remarkable anomalies. 



