1898.] SYSTEM or the chiroptera. 61 



The average measurements of this species are given in Dobson's 

 Catalogue. Two of my specimens measured : — Specimen A. 

 Adult male. Length, circa 210 mm. ; interfemoral membrane 10 ; 

 head 72 ; ear 38 ; eye to tip of nostril 29 ; forearm 147 ; thumb 

 64-5 ; 3rd finger 183 ; tibia 65 ; foot 51. 



Specimen B. Adult rnale. Length, circa 225 mm.; interfemoral 

 membrane 15 ; head 72 ; ear 38 ; eye to tip of nostril 29 ; forearm 

 155 ; thumb 65-5 ; 3rd finger 292 ; 5th finger 205 ; tibia 71 ; 

 foot 49. Weight, 10| oz. (spirit-specimen). 



Thoracic Viscera. 



The thorax in the Chiroptera is very much wider and more 

 capacious than is usual in the Mammalia. Pteropus medius de])arts 

 somewhat from the type, the thorax becoming longer and narrower, 

 but still remaining very large. The thoracic viscera are corre- 

 spondingly formed. The heart in this species is rather larger, and 

 the lungs smaller, than is usual in the Order. 



The Pleura. 



Composed, as is usual, of a parietal portion, lining the thoracic 

 cavity, and a visceral, clothing the surface of the lungs. But a 

 certain degree of complexity is associated with the reflexion of 

 this membrane from the upper aspect of the sternum, owing to 

 the shape and disposition of the lungs and the relation to it of 

 the so-called thymus gland. 



Both parietal pleurse pass upward together from the dorsal 

 aspect of the sternum. Tracing first the pleura of the left side, 

 anteriorly it passes upwards and to the left, and continued on the 

 wall of the thorax is reflected on the anterior ^ surface of the 

 pulmonary root, as in man. But owing to the projection across the 

 mesial plane of the upper lobe of the left lung, the left pleural 

 sac is carried to the right for a corresponding distance. On the 

 ventral aspect is situated a portion of the thymus gland ; a small 

 tongue of the same gland extends forwards on its dorsal surface. 



Posteriorly, the ])leura passes to the left, lying ventral to the 

 main part of the thymus and the pericardium, and then upwards, 

 the line of reflexion from the diaphragm being 11 mm. to the 

 left of the middle line. From this portion of the pleura the 



auditif chez les Mammiferes," Journ. de I'Anat. et Physiol. 1893, pp. 180- 

 220, pis. iv.-vi. 



Home, Sir Eveeard. — Lectures on Comparative Anatomy. London, 1814, 

 vol. i, pp. 158-160, vol. ii. pi. xx. (stomach of Pteropus and Plecotus). 



Cattaneo, Gr. — " Sull' Anatomia dello Storaaco del Pteropus medius," Atti Soc. 

 Ligustica, i. pp. 142-149. — Wunderlich, L., " Die Fortpflanzmig der Flughunde 

 {Gynonycteris collaris, 111., and P.medms, Temm.) im Zool. Gart. zu Eolu," 

 Zool. Gart. xxxii. pp. 78-82. 



1 These terms suppose the animal to be placed vrith the ventral surface down- 

 wards, " above" being therefore synonymous with " dorsal to "; " anterior " and 

 " in front of" corresponding to " on the cephalic side of." 



