1908.] DR. KNUD ANDERSEN ON BATS. 



249 



farther than represented in fig. 51) :— the two skulls of A. j. 

 pahnarum figured are from the same place (Macuto, La Guaira, 

 Venezuela) ; the one (fig. 50) is of an adult female with the distal 

 epiphyses of the metacarpals ossified, but the teeth unworn, i. e. a 

 mature but young individual; the other (fig. 51) an older male 

 with somewhat worn teeth : these two skulls have been selected as 

 paradigmata, because they belong to the same geographical race 

 of A . jamaicensis and were obtained precisely at the same locality ; 

 but perfectly similar extremes are found in other skulls of the series 

 examined, and not only in A. j. imlmamm but in A. j. litiiratus 

 as well (f. i. in a British Museum series of this latter race, from 

 Sapucay, Paraguay). The skulls figured are, the one of a female, 

 the other of a male, but the modifications have nothing to do with 

 sexual difierences. In the rather younger individual (fig. 50) the 

 brain-case makes the impression of being lower, the naso-frontal 

 depression (on the dorsal face of the rostrum, in front of the 

 sagittal crest) is shallow ; the supraorbital ridges, where starting 

 from the anterior point of the sagittal crest, form an angle with 

 this latter of about 125°-135°, the postorbital processes are very 

 inconspicuous (in still younger individuals scarcely indicated). In 

 the somewhat older individual (fig. 51) the brain-case makes the 

 impression of being higher, more vaulted, but the difierence 

 is more apparent than real, chiefly due to the higher and more 

 forwardly extending sagittal crest. This latter fact, that the 

 sagittal crest has been produced farther forward, has two 

 other efiects — first, that the naso-frontal depression (viewed in 

 profile) is more abrupt ; second, that the supraorbital ridges 

 are not directed forward and outward, but almost straightly 

 outward, forming an angle with the sagittal crest of very little 

 more than 90°; the postorbital processes are very conspicuous, 

 and a pair of comparatively large anteorbital processes has been 

 developed. 



The adult and old age modification of the skull as described 

 above is characteristic of the forms called in this paper the 

 " southern races " of ^ . jamaicensis (viz. A . j. lituratus, 2Kdma7'tmi, 

 prceceps). The transition from the young to the old stage takes 

 place earlier in some individuals than in others; I have seen 

 individuals with somewhat worn teeth which have still almost 

 the young type of skull, or are only in a transitional stage, 

 while others with almost quite unworn teeth have already 

 reached far on the way towards the old ag-e type. — The " northern" 

 races {A. j. parvij)es, yucatanicus, jamaicensis^ ceqitatorialis) 

 never, or exceedingly rarely, reach that degree of old age modifi- 

 cation of the skull attained by the southern races. 



A. j. parvipes, yucatanicus, jamaicensis, smd mquatoriahs retain, 

 throughout the whole life, a shape of the facial portion of the 

 skull not very different from that of immature individuals of all 

 races; in A. j. liUiraU(jS, pahnarum, and dominicanus the skull of 

 aged individuals is very conspicuously modified. From this it 

 is concluded that the former group of races, in this particular 



