vor,. XVI 

 1893 



^'•] PROCEEDINGS OF THE NATIONAL MUSEUM. 17 



efte(!ts ail iiiiportaiit articulation with the cai'tihij^c- of the tirst rib and 

 iu tlie steruo-claviculo-costal Joint; in Molossi, at least, it is of enormous 

 strength. Tha scapit la, sls iu other clavieulate forms, with few excep- 

 tions, in which tlie hirj»e anterior extremity is not sup[)()rt('(l on the 

 ground, possesses an infraspinatus fossai very nuich larger than the 

 supraspinatus. The bone lies well up on the side of the. neck iu the 

 forms in which the ccrvitial series of vertebra' is bent forward. Excel- 

 lent characters are yielded by thecoracoid process. It is always lougaud 

 slender, simple, and gently curved in various arcs in L*teroi)id8e, lihi- 

 noloidiidu', Emballonurida', and Phyllostomidu', but bifid in most 

 Vespertilionida'. It is interesting to find tlie genus Fc'.s7>6T^//*o aber- 

 rant in this respect, the process being simple and curved quite as in 

 the larger groups first named. The posterior tubercle is ])rolonged to 

 form an obliciue posteriorly-directed process in the molossines and in 

 Chdlinolohus. 



With the exception of the tuberosities of the humeruH no check 

 processes exist anywhere in the bones of the limbs, tlius pn^senting 

 marked contrasts with tlie limbs of birds. Tlie trochlear end of the 

 humerus yields in the shape and direction of the (;i)itrochlea valuable 

 characters. This process conforms to the terrestrial type, i. c, it is 

 transversely inclined in pteropines and the genus Saccopteryx; is de- 

 flected downward parallel or nearly so to the shaft in i)hyllostomines, 

 but is absent in vespertilionines. In vespertiliouines again the articu- 

 lar surface is axial, /. c, is in the middle line of tln^ humerus, but in 

 phyllostomines it is thrown well off to the outer side. Narrow-winged 

 forms, as the molossines and the genus Atalapha, exhibit large tubercles 

 on the humerus and wide trochlear surfaces. Thus these charac'ters 

 harmonize Avith rapid flight. On the otlier hand, the forms with smaller 

 tubercles and narrow poorly defined trochlear surfaces have broad 

 wings and presumably slow flight. 



The radius constitutes the main support of the forearm and pr<'sents 

 few variations from a single type. As a rule it is nearly straight, but 

 is much bent in HipposideroH. It is always obliquely grooved by the 

 tendon of the extensor ossi metacarpi pollicis. The size of the large 

 deep fossa for the insertion of the biceps flexor is variable. Since the 

 ulna does not enter into the composition of the anterior arc of the 

 trochlea, and its place is here taken by the radius in addition to tlie 

 work this bone does in articulating with the humerus at its outer half, 

 it is easily seen that the radius is provided with two facets at its ])rox- 

 imal end, and that the main ridge on the distal articular surface of the 

 humerus fits in between these two radial facets. So far as the degree 

 of invasion of the radius into the trochlea has been noted it appears tq 

 correlate with the degree of activity of the prone form in scurrying. 

 It is thus market} ii^ Gheiromeles and MoIohsuk^ and is small in 

 Kerivoula. 



Proc. $^, M. oa-.— 2 



