128 



V. Sexual Differences. 



The male and the females of Chelifer Geof. are generally very easily discerned 

 from each other both by primary and secondary sexual characters. 



When a full-grown specimen is observed from beneath, it is generally possible 

 to determine the sex by a superficial investigation of the genital area, because 

 that of the female is less conspicuous than that of the male. But as the sexual 

 apparatus of the male in contrast to that of the female differs so vastly in the 

 différent groups of species (cf. pp. 121 — 124), 1 think, that a proper knowledge of 

 these variations as well as some practice are to be wished for, before being able to 

 determine the sex in this manner with certainty, if both are not represented. The 

 sexual difference is in this respect as in others most evident in "Lophochernes Sim." 

 (PI. Ill, fig. If); it is also well marked in C/i. Birmanicus Thor., but less so in Ch. 

 cimicoides F. and Ch. subruber Sim. Respecting this theme I also refer to Crone- 

 berg (45. p. 448) and Hansen (49. p. 235). 



With regard to the secondary sexual characters it ought to be stated at once, 

 that only a few can be applied to all species; the greatest number is onh' of value 

 within a smaller or larger group of species, sometimes only in a single species. 

 A character, which is of small value in the not quite full-grown specimens, is 

 often very conspicuous, when the female has the abdomen distended by eggs, 

 namely the shape and the size of this. 



Tergal keels. — Simon seems to have been the first, who observed the 

 longitudinal keels, with which the first tergites of a species of Chelifer Geof. are 

 adorned; he made it on account of this structural feature to the representative of 

 a new genus and called it Lophochernes bicarinahis Sim. (1878. 25. p. 66). Hansen 

 described (1884. 9. p. 521) the well developed keels in the males of Ch. deprcssus 

 C. K. and Ch. granulatus C. K., and the almost obsolete ones in Ch. lainpropsalis 

 L. K. Thorell has observed that the first abdominal tergites of Ch. hians Thor, are 

 keeled (1891. 13. p. 355), but seems not to have understood that this character is 

 only a sexual one. Hansen has later on given a figure of the abdomen of the male 

 of Ch. granulatus C. K., showing the arrangement of the keels (1894. 49. tab. IV, 

 fig. 12), and Lewis figured a species Ch. sculpturaius Lew. , in which these keels 

 attain a high degree of development (1903. 69^. pp. 497-498, pi. XXV and 21. p. 120). 

 Ellingsen has in a small treatise (1901. 18. p. 205) described such keels in his Ch. 

 Borneonensis Ell. and made some historical remarks on this theme. These struc- 

 tures are very prominent in Ch. depressus C. K., in which teeth or well developed 

 keels are present in the two thoracic as well as the five first abdominal tergites 

 (PI. Ill, fig. 2 a, /' ') and will as well as those of Ch. Morlensenii n. sp. and Ch. super- 

 bus n. sp. with variety be described under each species respectively. 



5. Ch. granulatus C. K. (cf. 49. tab. IV, fig. 12). — The first thoracic tergile has 

 neither teeth nor keels, bul the second has at least in some specimens the posterio- 

 lateral corner prolonged into a fairly well marked tooth or spine, which is directed 



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