706 HEPOET — 1888. 



■witliin certain limits, rightly constructed abdominal bands are of use, and are not 

 an abuse. They have not touched upon the jmthologij of abdominal constriction, 

 this subject not being in the scope of their paper. 



Zoological Depaetjient. 



1. Some BemarTcs on the Instincts of Solitary Wasps and Bees. 

 By Sir John Lubbock, Bart, F.B.S. 



2. Bestoration o/ Brontops Robustns, />o?)z the Miocene of America, 

 Bij Professor 0. C. Maksh, Fli.B., LL.D. 



The largest mammals of the American Pliocene were the huge Brontotheridce, 

 ■which lived in great numbers on the eastern flanks of the Rocky Mountains, and 

 were entombed in the fresh- water lakes of that region. They were larger than the 

 Binocerata of the Eocene, and nearly equalled in size the existing elephant. They 

 constitute a distinct family of perissodactyles, and were more nearly allied to the 

 rhinoceros than to any other living forms. 



The deposits in which their remains are found have been called by the author 

 the Brontotherium beds. They form a well-marked horizon at the base of the 

 Miocene. These deposits are several hundred feet in thickness, and may be 

 separated into different subdivisions, each marked by distinct genera or species of 

 these gigantic mammals. 



The author has made extensive explorations of these Miocene lake-basins, and 

 has secured the remains of several hundred individuals of the Brontotlieridce, which 

 will be fully described in a monograph, now well advanced towards completion, to 

 be published by the United States Geological Survey. Tlie atlas of sixty litho- 

 graphic plates is already printed, and the author submitted a copy to the Section. 

 The last plate of this volume is devoted to a restoration oi Brontops robustus, one- 

 seventh natural size, and a diagram enlarged fi-om this plate to natural size was 

 also exhibited. 



The skeleton represented in this restoration is by far the most complete of any 

 of the group yet discovered. It was found by the author in Dakota in 1874, and 

 portions of it have been exhumed at different times since, some of tlie feet bones 

 having been recovered during the past year. It is a typical example of the family, 

 and shows well the characteristic features of the genus and species which it 

 represents. 



The most strildng feature of the restoration here given, aside from the great 

 size of the animal, is the skull. This is surmounted in front by a pair of massive 

 prominences, or horn-cores, which are situated mainly on the frontal bones. The 

 nasals contribute somewhat to their base, in front, and tlie maxillaries support the 

 outer face. These elevations, or horn-cores, vary much in size and shape in the 

 difi'erent genera and species. They are always very small in the females. 



The general form of the skull and lower jaw is well shown in the figure. The 

 prominent occipital crest, the widely expanded zygomatic arches, and the projecting 

 angle of the lower jaw are all characteristic features. In general shape the skull 

 resembles that of Brontot/ierimn, but may be readily distinguished from it by the 

 dental formula, which is as follows: — 



Incisors | ; canines \ : premolars J ; molars |. 



The presence of four premolars in each ramus of the lower jaw is a distinctive 

 feature in this genus. This character, with the single well-developed lower incisor, 

 marks both the known species. 



The number of teeth varies in the different genera. The form of the teeth, 

 especially in the molar series, is more like that in Chalicotherium and Diplacodon 



