Mr. A. Tulk on the Anatomy of Phalangium Opilio. 323 



cheurs), the latter author has described at length and in very gra- 

 phic language the preliminary contests among the males and sub- 

 sequent copulation between several individuals of P. cornutum and 

 Opilio. His concluding words are, " D^autres individus celebrent 

 aussi leurs noces en ma presence, et le fait que j^ai avancee ne 

 saurait etre contestee." Treviranus explains these conclusions 

 of Latreille, to which he was led, in the first place, by having 

 met, in dissection, with male organs only in P. cornutum and 

 female in P. Opilio, by observing that the separate occurrence of 

 the sexes at certain periods is not uncommon among apterous 

 insects, and further, that a hybrid union might have been taking 

 place among the specimens witnessed by that observer. If in- 

 deed this conjecture be correct, it is not surprising that the ano- 

 malous fact of several individuals of opposite species, though very 

 different in outward form, congregated for the purpose of copu- 

 lation with each other, should have deceived even so accurate 

 an observer as Latreille. From what little I have observed myself 

 of these two species, I believe they are essentially distinct from 

 each other. I have already pointed out the slight modifications 

 of external form which characterize the sexes of P. Opilio, and 

 among the numerous specimens of the latter which I have dis- 

 sected, have met with a very fair proportion of males to females. 

 With regard to P. cornutum, which is abundant in pastures and 

 on the chalk hills under stones about Dover, I seldom met with 

 P. Opilio associated with it, this species affecting rather the 

 whitened walls of outhouses than the open country. Hermann, 

 Herbst and Hahn, all moreover describe these species as distinct ; 

 the latter indeed has given drawings of the male and female of 

 P. cornutum, observing of them, ^^ beide Geschlechter traf Ich oft 

 in Begattung an ;" and of P. Opilio, " Nach Latreille soil diese 

 Art das Weibchen von P. cornutum seyn, allein Ich traf solches 

 noch niemals mit Jenem in Begattung, wohl aber sehr oft die 

 beiden Geschlechter dieser Art mit Brust an Brust gedi'iickt, und 

 mit den Fiihlfiissen sich umklammemd im Begattung an." 



In his description of the position of the bodies of the male and 

 female during coition, Hahn in the passage just quoted has con- 

 firmed the observations made upon this point by Latreille, who 

 furnishes, however, in addition the following remarkable though 

 rather indistinct statement : — " L'accouplement a lieu et dure 

 trois a quatre secondes. II n'en resulte aucune adhesion comma 

 dans un grand nombre d^insectes. La reunion vient de s^operer, 

 et le male ne laisse apercevoir aucune marque caracteristique de 

 son sexe." The inference from this is, that no actual introduc- 

 tion of the male organ into the vaginal orifice of the female is 

 effected ; and certainly, when the position of their bodies is taken 

 into account, and that the glans of the male, with the opening for 



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