Vörös A. szerk.: Fragmenta Mineralogica Et Palaentologica 11. 1983. (Budapest, 1983)

Skull and upper dentition of Myotis exilis Heller, 1936 On the ground of the previous study of the mandibles and the Gundersheim type-material of HELLER, it is stated with high certainty that one of the commonest small Myotis in the Middle Pliocene of Osztramos is M. exilis

. Based on analogies between mandibles and maxillary fragments and even on scattered remains where the corresponding mandible and rostrum were found together, I could identify the upper dentition and I give here a description of the skull of M. exilis (Plate I, Figs. 1,2,3). Its similarity with M. mystacinus (Kuhl, 1819) is striking at the first glance. There are, however, a good number of features for distinguishing them. The most important differences are the greater size, the robust form and the broadness of the skull in the fossil animal. Its rostrum is 3 3 wide especially at C-C. The M

J-M width is also greater tahn that of the recent form. Its anteorbital bridge is narrower than in the recent species. There is a strong sagittal crist on the doomed braincase. It originates nearly above (while a much weaker sagittal crist of M. mystacinus well beyond) the interorbital constriction. The backward projecting portion of palate is wide and shorter than that of the recent animal. The anterior palatal emargination is shroter and wider than in the recent one and does not reach even the level of the anterior one-third length of canine alveolus, while in the recent one it reaches the level of one-half length of alveoli. The small premolars are more or less tightened as much as in the recent form, and in some cases pressed inwards from the tooth-row line. P

4 has a more or less strong antero-internal cusp which is anteroposterior^ in one line with the main cusp, as in M. mystacinus

. M and M

2 have angular margin lingually, due to the strong hypocone on the postmetaconule wing. There is a very strong and high ridge in M^ and M

2 between protocone and metacone, with even some hint of metaconule. The ridge is probably homologous with van Valen's postprotocrista and premetaconule wing. Moreover, a more or less developed low bar is there, probably the centrocrista, between the postparaconule wing and premetaconule wings (see: VAN VALEN 1 966, p. 8). All these structures are absent in the upper molars of M. mystacinus

. Otherwise, the more or le.ss well-developed paraconule (=protoconule) is always present in the upper molars of exilis (weak in M* and strongest in M

3

) and much less pronounced in mystacinus

. A comparison with M. helleri from Osztramos shows complete and absolute differences between the two species in interorbital constriction and in C-M

3 length, where helleri has greater values. The crown of upper C is in exilis stronger than that of helleri

, however with some overlap. The other rostral and maxillary measurements extensively overlap. Myotis janossyi sp. n. Derivatio nomitis

; The species is dedicated to Dr. Dénes JANOSSY, under whose guidance the excavations at Osztramos Hill were performed, and who carried out extensive scientific work on the faunas obtained there. Stratum typicum and locus typicus

; Estramontian horizon of the Middle Pliocene, Osztramos Locality 13, NE Hungary. Diagnosis

: A small Myotis related to M. brandti (Eversmann, 1845), but with broader rostrum and narrower interorbital constriction. Holotype

: A well-preserved skull with broken-off zygomatic arch and injured braincase, missing cochleae and bullae (Plate I, Figs. 4, 5, 6). All its incisors, canines and the one-rooted premolars are missing. Deposited in the Collection of the Palaeontological Department, Hungarian Natural History Museum, Budapest. No. V. 82. 169. Measurements of the holotype: Total length of skull 13.82 mm, condylobasal length 13.10, zygomatic width 8.60. interorbital constriction 3.71, braincase width 7.20, braincase height 5. 01, lacrimal width 4. 39, rostral width at C-C (alveoli) 3. 70, rostral width at M

3-M

3 (crowns) 5.74, length of narial notch 1.40, width of narial notch 1.45, length of anterior palatal emargination 1.40, width of anterior palatal emargination 1.27, shortest distance between C alveolus and anterior emargination 0.63, palatal width beyond toothrows 2.03, distance