FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 135 



molars invite comparison with the Phyllostomatidae, although they 

 do not prove that a real relationship exists. The character of the 

 antemolar dentition distinguishes the Picrodontidae sharply not only 

 from the Phyllostomatidae but also from all other Chiroptera. 



The affinities of the Picrodontidae are wholly dubious at present. 

 They compare in a very broad and general way with the Insectivora, 

 Chiroptera, and Primates. Reference to the Primates is merely a 

 possibility, with no positive evidence to commend it. Evidence for 

 reference to the Chiroptera is seen in the phyllostomatidlike molars 

 but is reall}^ very tenuous and does not at present warrant the extraordi- 

 nary conclusion that the Chiroptera had already in the Middle Paleo- 

 cene achieved tliis peculiar and aberrant molar pattern and at the 

 same time had lost, or not yet acquired, characters otherwise universal 

 among chiropterans. Such references, even when circumspectly 

 expressed, are moreover likely to be misleading, for they inevitably 

 are restated in more general works by authors not acquainted with the 

 original material, in some such form as "Specialized phyllostomatid 

 bats were already present in North America in the Middle Paleocene", 

 without the necessary addition that the evidence actually falls far 

 short of proof. It is more conservative and less prejudicial to future 

 work to refer the Picrodontidae to the ?Insectivora, using Insectivora 

 in its scrap-basket sense, pending discovery of more conclusive indica- 

 tions of affinity. When these are discovered, they are (as far as can 

 be foreseen) as hkely to point to the Insectivora as to any other order. 



Genus PICRODUS Douglass, 1908 



Picrodus Douglass, 1908, p. 17. 

 Megopterna Douglass, 1908, p. 18. 



Type. — Picrodus silberlirigi Douglass. 



Type o/ Megopterna. — Megopterna minuta Douglass. 



Distribution. — Middle Paleocene, Fort Union, Montana. 



Diagnosis. — Enlarged, procumbent anterior lower tooth, followed by 

 three or four small teeth, the most posterior (P4?) 2-rooted but small 

 and simple. Mi much enlarged, with a small, elevated, and procum- 

 bent trigonid with three poorly differentiated cusps, heel elongate and 

 large, with a curving crest and two vague internal cuspules, basin not 

 closed. AI2 with lov/er, subquadrate but 3-cusped trigonid, large, oval, 

 basined talonid with crest and two internal cusps. Enamel of both 

 talonids papillated. 



Remarks. — From Douglass' specimens and, still more, his some- 

 what diagrammatic figures it would appear altogether impossible that 

 Picrodus and Megopterna should be synonymous, but this is shown to 

 be true bej^'ond any question by the larger series of specimens now 

 available. The type of Picrodus included P4 and Mi, the latter im- 

 perfect, and that of Megopterna included M2 and a small fragment of 

 119212—37 10 



