66 Proceedings of the Biological Society of Washington. 



pit near middle of posterior border, and without the descending processes 

 which in Tapirus meet and overlap the ascending branches of maxillae; 

 maxillary floor of orbital fossa rising nearly to level of orbital border of jugal; 

 posterior nares much elongated as viewed from below, and opening directly 

 downward (shorter and directed downward and backward inTapirus and 

 Tapirella) ; maxillo-turbinals deeply plicated, the internal folds and alter- 

 nating furrows of similar width (in Tapirus the furrows are separated 

 by very narrow trenchant ridges; in Tapirella the maxillo-turbinals are 

 smooth); transverse divisions of upper molars thick, the posterior walls 

 less broadly excavated than in Tapirus and Tapirella ; first upper pre- 

 molar with a broad anterior cusp; third upper molar with outer cusps 

 laterally compressed and connected by a high trenchant ridge, much as 

 in Tapirella, instead of conical and separated by a deep notch as in 

 Tapirus. 



Remarks. — Among the most important and readily apparent cranial 

 peculiarities distinguishing the three genera of existing tapirs are the dif- 

 fering arrangement of the bony parts supporting the proboscis. In Acro- 

 codia and Tapirella the nasals are flat, triangular bones without the stout 

 descending processes which in Tapirus meet and overlap the maxillae. 

 In Acrocodia and Tapirus the maxillae are not developed upward in thin 

 vertical plates embracing an anterior ossified extension of the mesethmoid 

 as in Tapirella. Skulls of Acrocodia are thus distinguished by the ab- 

 sence of descending nasal processes and vertically ascending maxillary 

 plates. In dentition the genera are much alike; Acrocodia in dental 

 detads seems nearer to Tapirella than to Tapirus. 



The three genera represent the surviving branches of a family whose 

 former range included much of Europe and North America. Tapirs appa- 

 rently became extinct in Europe§ before the Pleistocene period, as none of 

 their remains have been found in the caverns or alluvial deposits in which 

 those of elephants, rhinoceroses, and hippopotamuses occur in abund- 

 ance. The genus Tapirella is known only from the tropical parts of 

 Middle America, from eastern Panama northward to southern Mexico. 

 Tapirus terrestris ranges widely in tropical South America and the genus 

 is represented in the high Andes by T. roulinii Fischer, a species with 

 remarkably flattened braincase, but agreeing in essential generic charac- 

 ters with typical Tapirus. In northwestern Colombia and eastern Panama 

 the distribution areas of Tapirus and Tapirella probably meet or overlap. 

 Acrocodia is now restricted to southeastern Asia and islands of the East 

 Indies, and its isolation therefore is measured by the full width of the 

 Pacific Ocean. 



* Wagler (Nat. Syst. Amphibien. p. 17, 1830) quoting other authors says: " Nomina 

 generica, quae ex graeca vel latina lingua radicum non habent, rejicienda sunt." 

 tProc. Zool. Soc. Lond., p. 884, 1867. 

 t'AKpos, high; /cuiSeta, head. 

 § Flower and Lydekker, Mammals Living and Extinct, p. 372, 1891. 



