1918.] F. H. Gravely : Passalidae of the World. 



89 



■• The tips of all six lamellae forming a straight line when the 



antenna is furled ; the anterior marginal depressions of the 



mentum always large and separate ; the sides of the elytra 



hairless .. .. .. ., ># Q singapurae, p. 87 . 



The tips of the first two lamellae not falling in line with those 



of the other four when the antenna is furled ; the anterior 



marginal depressions of the mentum very variable, often fused 



or rudimentary ; the sides of the elytra densely hairy in front 0. wallacei, p. 87. 

 The anterior marginal depressions of the mentum very large ; 



the sides of the elytra hairless . . . . .. 0. inaequalis, p. 87. 



The anterior marginal depressions of the mentum more or less 



rudimentary ; the sides of the elytra hairy . . . . . . . . o. 



The upper tooth of both mandibles well developed, more or 



less rectangular ; the frontal area markedly transverse . . 0. aequalis, p. 88. 

 The upper tooth of both mandibles rudimentary or at least 



more obtuse ; the frontal area about as long as broad . . . . . . 7. 



The anterior lower tooth of the left mandible very large, much 



larger than that of the right mandible . . . . . . . . 8. 



The anterior lower tooth of the left mandible scarcely larger 



than that of the right . . . . . . . . 0. aequidens, p. 88. 



The upper tooth of the left mandible obtuse but moderately 



large ; the seventh ribs of the elytra almost unpunctured . . 0. javensis, p. 88. 

 The upper tooth of the left mandible minute ; the seventh ribs of 

 the elytra sparsely punctured and hairy throughout . . 0. minor (Gravely). 



Genus ACERAIUS. Kaup, 1868a, pp. 26-27. 

 Type, Passalus grandis, Burmeister, 1847, p. 463. 



Acerai us lamella tus n. sp. 



Mr. Holman-Hunt has submitted two specimens from the Malay Peninsula (Ulu 

 Gombak), and Mr. Bryant two from Penang, one of each of which has been presented to the 

 Indian Museum collection. Length 23 mm. 



This species appears to be allied to various species of the genus Ophrygonius on the one 

 hand, and to the genus Aceraius on the other. The antennal lamellae and mentum resemble 

 those of Ophrygonius singapurae, the former being exceptionally large for so small an 

 insect. The mandibles are of the Aceraius type, ana resemble those of A. helferi except that 

 the convexity of the posterior part of the upper margin is pressed further back from the small 

 upper tooth. In other respects this species resembles Ophrygonius minor, except that the 

 eighth ribs of the elytra are punctured instead of (or as well as) the seventh. 



Aceraius helferi, Kuwert 

 PI. I. 



Aceraius helferi, Kuwert, 1898, pp. 346-347. 



Aceraius helferi + tavoyanus + assamensis + himolayensis, Gravely, 1914c, pp. 236-238, pi. xii, 

 figs. 36-39a. 



One specimen from Burma and four from Siam, three of the latter being from Renong. 



M. Vitalis de Salvaza has presented a fine series of this species from Tonkin (Chapa 



and Xieng Khouang), and has sent for examination specimens from Ban Tink and Lao 



N 



