Mouth 31 



carina stomothecre (r/), which is marked off by a groove, and of which the anterior ex- 

 tremity often forms a projecting point. Thorell has ah-eady (c, p. 24, note 2) drawn attention 

 to the feet that the shape of stomotheca is different in different genera; but even within 

 the genus Stylocellus, the only one of which a larger number of species are known, small 

 differences in this respect are noticeable between the species. In Laniatores stomotheca is 

 not very well defined ; in Palpatores a stomotheca is hardly formed, except in Troguloida; 

 where it is very well developed. 



As the structure of the mouth in Cyphophthalmi has not been well described by 

 previous writers, we consider it desirable to begin by giving an account of this structure 

 in the other sub-orders of Opiliones. In this order generally the mouth is composed 

 of 1° a clypeus and a labrum, '2° the mandibles (maxillae auctorum), which meet in the 

 middle line beyond the distal extremity of labrum, and 3° the maxillary lobes of the first 

 pair of coxas which enfold the posterior part of the mandibles laterall}' and from behind. 

 In Laniatores and Palpatores these parts are supplemented by a prolongation of sternum, 

 labium sternale, which enters between the maxillary lobes of the first pair of coxse. In the 

 great majority of Opiliones the coxae of the second pair are furnished with maxillary lobes, 

 but these are always placed outside and behind the mouth proper. A characteristic feature 

 is that all the parts which sin-round the oral cavity, viz. labrum, mandibles, maxillary lobes 

 of the first pair and labium, where it exists, terminate in soft thin-skinned and therefore 

 white portions, which turn inwards towards the cavity of the mouth, but besides are sometimes 

 continued outside the border of the oral cavity, in the shape of soft cushions. On the maxillary 

 lobes of the second pair of coxiB no such soft part is ever found. When the mouth opens 

 the mandibles are moved a little forwards and away from each other, whilst the maxillary 

 lobes of the first pair of coxa? are moved a little outwards and backwards, whereby the orifice 

 of the mouth is placed partly between the mandibles and the maxillary lobes of the first pair 

 of coxae, partly also between the mandibles themselves. 



The mandibles are essentially alike in all Opiliones, their pars manducatoria being placed 

 outside clypeus and labrum and bent downwards and backwards. 



The ma.rillary lobes of the first pair of coxce on the contrary offer considerable differences 

 in different divisions of the order. In Palpatores they consist of three portions : a soft distal 

 one and two more or less chitinized parts, a basal and a more distal one. Simon (b, p. 124) 

 has already pointed out this fact as regards PhalangioidiB. Of the two chitinized portions 

 the distal one is movable in all Palpatores. In Phalangioidse (woodcuts figs. A and B) the 

 basal portion is besides movably connected with coxa. In several genera of this family the 

 basal portion carries anteriorly and distally a projection in the shape of a horn (woodcut fig. B) 

 which is not found in other general In Phalangioidse the two more firmly chitinized por- 

 tions of the maxillary lobe are almoist of the same length, measured from the base to the 

 distal margin ; but in Ischyropsalis, Nemastomatoidas, and Troguloidaj (woodcut fig. I), the 



1 The horn is found in AcantholopMis, where it is small, in have two horns, for instance Ph. opilio L. (see woodcut A), 



Phalangium and Mitopus, but not in Sclerosoma, Gagrella this is far from being the case with all. Ph. parietinum de 



3.nA. Leiohunum. — Simon (i, p. 158) enumerates amongst other Geer, for instance, has only one. What Simon in this and 



characters of his sub-family SclerosomatioEe, that the mandible similar cases has mistaken for a second horn on the mandible 



("lobe maxillaire de la patte machoire") is furnished with is the horn mentioned above as occurring frequently on the 



only one horn (" tubercule"), whilst Phalaiigiinaj, according maxillary lobe of the first pair of coxse. 

 to him, have two such. But, though some of the latter really 



