No. 2304. REPTILIAN CHARACTERS IN MAMMALS— WORTMAN. 19 



skull of Nycticehus (No. 142240) and of a Perodidicus (No. 184229) 

 this lower piece is shown on both sides with the remains of the suture 

 distinct. In the South American primates with the large malar 

 vacuity, when the malar consists of more than a single piece, the 

 parts are arranged in such a way as to radiate from the malar opening. 



Not infrequently there is a suture in certain species of South 

 American apes, cutting off that part of the malar which lies upon 

 the orbital rim, below and to the outside of the eye cavity, and less 

 frequentl}^ an element which lies behind the malar foram.en near the 

 junction of the m.aiar with the squamosal. In a like manner there 

 is often evidence of a distinct element extending from the supraorbi- 

 tal foramen to the junction of the malar, upon the upper and outer 

 edge of the orbital rim. I can find no traces of a premallear element 

 nor paramastoid in any specimens of primates which I have examined. 



Movotremes. — The skull of the duckbill (OrnithorJtynchus paradoxus) 

 exhibits a number of features wliich are of great interest in connection 

 with the present study. On account of the early coossification of 

 nearly all the cranial bones and the obliteration of the sutures it is 

 not easy to determine their limits and relations from the ordinary 

 museum specimens. The only figures purporting to give this informa- 

 tion are from Van Bemmelen ^ and Broom,^ but these are so different 

 from that of a fairly young specimen in the collection that I have 

 deemed it advisable to give the interpretation of certain of the 

 elements as afforded by this skull.^ The zygomatic arch as here 

 shown is composed of the three elem.ents already described in 

 Khynchocyon , and while there may be some doubt in regard to the 

 division of what appears to be the long zygomatic process of the 

 squamosal running forwards to the postorbital process of the arch, 

 yet the specimen shows what appears to be the remains of a suture 

 in the situation where it should appear. The supposed backward 

 extension of the maxillary process to the glenoid articulation in the 

 lower part of the arch, as figured by Broom, is shown to be a dis- 

 tinct element separated from the maxillary by a well-marked suture. 



That which is the most important and interesting feature of the 

 skuU before us, however, is an indication of the presence of a rela- 

 tively large distinct bone lying just internal to the glenoid cavity, 

 between it and the periotic; it projects downwards and backwards 

 and the appearance of the surface of its lower free extremity so 

 closely resembles that of a synovial joint that there is apparently no 

 mistaking its significance. This piece is distinctly separated by 

 weU-marked suture from the squamosal, the exoccipital, and the 

 alisphenoid, but in the present specimen not completely cut off from 

 the periotic. If it is not distinct from this latter bone in the still 



1 Ueber deu Schadel der Monotremen, Zool. Anz., 1901. 



2 Structure and Affinities of the Multitubcrculata, Bull. Amer. Mas. Nat. Hist., 1914, p. 130. 

 ^' Watson's paper was received too late for use in this connection. 



