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Show 734 MR. G E. DOBSON ON THE MOLOSSI. [Nov. 7, 21. NYCTINOMUS ACETABULOSUS. Molossus acetabulosus, Commerson, MS. Fide Peters, Monatsb. Akad. Berl. 1869, p. 402. Nyctinomus acetabulosus, Desmarest, Mammalogie, p. 117 (1820). Nyctinomus natalensis, Smith, Zoolog. S. Africa, pl. 49. Nyctinomus (Mormopterus) jugularis, Peters, P. Z. S. 1865, p. 463. Ears quite separate, arising from the sides of the forehead at a short distance above and in front of the eye ; the inner margin of the ear-conch slightly convex for two thirds its length, abruptly concave in upper third, so that the upper extremity of the ear is attenuated, and the subacute tip projects forwards and inwards, instead of backwards and outwards, as in most species of Bats; outer margin of the conch forming almost a straight line from the tip to its termination near the angle of the mouth, interrupted only by a slight emargination opposite the middle of the tragus, indicating the commencement of the antitragus; tragus nearly as broad as high, irregularly triangular, with a truncated vertical angle. Muzzle flat, extremity projecting considerably beyond the lower lip; sides of the upper lip with short ill-defined vertical wrinkles. In the male a large glandular sac in the centre of the inferior surface of the neck, in the female rudimentary. Wings from the distal third of the tibiae ; the fifth toe not so much thickened as the first. Fur dark reddish brown above, somewhat paler beneath. Upper incisors separate from the canines and also from each other; lower incisors small, slender, bifid, crowded ; the second incisor on each side slightly overlapped by the margins of the first and third ; canines without basal cusps ; the single upper premolar separated by a narrow interval from the canine, with a projecting base internally, which is concave behind and anteriorly develops an acute cusp; first lower premolar unicuspidate, equal to three fourths the second in vertical extent. Length (of an adult cS): head and body 1"*9 ; tail 1"7, tail free from membrane 0"*6 ; head 0"75 ; ear 0"*6, tragus 0"*15; forearm 1"*55 ; thumb 0"*25; second finger-metacarp. 1"*5, 1st ph. 0"*6, 2nd ph. 0"7; third finger-metacarp. 1"*5, 1st ph. 0"*5, 2nd ph. 0"*4 ; fourth finger-metacarp. 1"*15, 1st ph. 0"*4, 2nd ph. 0"*2 ; tibia 0"*4 ; foot and claws 0"*35. -Hab. S.E. Africa (Natal); Madagascar; Bourbon; Mauritius. • The three last-described species, N. norfolcensis, N. albiventer, and N. acetabulosus, differ from all the other species of the genus in the relative lengths of the metacarpal bones of the second and fourth fingers, resembling rather, in this respect, the species of the subgenus Myopterus (gen. Molossus). In all other species oi Nyctinomus the metacarpal bone of the second finger is double the length of that of the fourth; in these three species, and in Myopterus, it is but one half longer. These species also agree together in the form of the tragus (in which they also differ from all other |
