in 



behind. Palate toothless. One or two transverse dermal ridges 

 across the palate, in front of the pharynx. Tympanum in- 

 distinct or hidden. Fingers free, toes free or feebly webbed, 

 with disks. Outer metatarsals united. 



Procoracoids and clavicles present, the latter not reaching 

 the scapulae; no omosternum '). Terminal phalanges T-shaped. 



Distribution: from Celebes to New. Guinea. 



Synopsis of the Species. 



A. Toes free. 



I. Metatarsal tubercle absent. 



1. Tympanum 2 / 3 or 3 / 4 the width of the eye. I. 0. variabilis p. 112. 



2. Tympanum about '/ 3 the width of the 



eye, or hidden 2. O. celebensis p. 112. 



II. Metatarsal tubercle present. 



1. The heel does not reach the eye. Tym- 

 panum hidden 3-0. monticola p. 113. 



2. The heel reaches the eye or beyond. 

 Tympanum about l / 2 the width of the eye, 

 or hidden. 



a. First finger with a disk 4. 0. verrucosa p. 113. 



b. Tip of first finger not dilated 5. 0. ateles p>. 115. 



B. Toes webbed. 



I. The procoracoid reaches the scapula. 



1. Interorbital space much broader than the 



upper eyelid . 6. O. senckenbergiana p. 115. 



2. Interorbital space as broad as the upper 



eyelid "J. O. crucifcra p. 116. 



II. Procoracoid connected with the scapula by 

 a ligament only. 



1. Tympanum about '/ 2 tne width of the eye. 8. O. anthonyi p. 117. 



2. Tympanum about '/ 3 the width of the eye. 



a. Fifth toe extending beyond third. 



ct. The heel reaches the shoulder or 



the tympanum. 9. 0. loriae p. 117. 



(3. The heel reaches the eye 10. O. biroi p. 118. 



b. Fifth toe as long as third. 



ct. Two dermal palatine ridges. . . . II. 0. albopunctata p. 119. 

 (3. -One dermal palatine ridge .... 12. O. mertoni p. 120. 



I) The pectoral arch of 0. ateles, variabilis and monticola has not been 

 described; as to variabilis and monticola Dr. Boulenger informs me, that a 

 cartilaginous procoracoid is present, but that he cannot find a clavicle. The 

 position of these species in the genus therefore is only provisional. 



