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EUopostoma megalomycter (Vaillant). 



Aperioptus megalomycter Vaillant, Notes Leyden Mus. XXIV. 1902, p. 145. 



D. 3.16; A. 3.5; P. i.ii; V. 1.7; L.I. 65; L. tr.T. 



14 CO 

 Height 5, equal to head, 6.3 in length with caudal. Eye 3.2, 



slightly longer than .snout and equal to interorbital space. 



Dorsal nearly half higher than length of head ; its origin before 



that of ventrals, separated by about 20 scales from occiput. 



EUopostoma megalomycter (Vaill.). (After Vaillant). 



Height of anal slightly less than length of head. Ventrals equal 

 to head, separated by 8 scales from lateral line, surpassing 

 anus. Pectorals somewhat longer than head, not reaching ventrals. 

 Caudal much longer than head. Least height of caudal peduncle 

 somewhat less than its own length and more than twice in 

 head, surrounded by 24 scales. Silvery, with about 2 irregular 

 series of dark patches of different size and form on the upper 

 half of the body. Length 5 i mm. [Type of the species in the 

 Leiden Museum seen by us]. 



Habitat: Borneo (river Kapuas!). 



Note: Vaillant places this species in the enigmatic genus 

 Aperioptus Rich, (see p. 238). We think there is no reason to 

 do so. We therefore use for it the name EUopostoma^ which 

 Vaillant proposed in case his fish should appear not to be 

 an Aperioptus. 



In the second place Vaillant brings Aperioptus and there- 

 fore also EUopostoma in the family Cobitidae. We doubt the 

 correctness of this view, although we are not able to say, to 

 which family of Cyprinidae these probably young fish belong. 



