Eijes 35 



they form therefore almost right angles with cariiKr stomothecse. As this difference in their 

 position coincides with the fact that the second pair of coxae are immovable in Styloceliini, 

 hut capable of movement in Sironini, there can be little doubt that the movability or the 

 contrary of the second pair of coxse is of importance, in some way or other, for the action 

 of the mouth, but we are unable to suggest in what the importance may consist. The 

 maxillary lobes of the second pair of coxeb are never movable in Cyphophthalmi, nor are they 

 furnished with a soft terminal part ; but they are clearly, though not sharply, marked off from 

 the rest of coxa. 



It will be seen that as regards the structure of the mouth Cyphophthalmi differ in several 

 points from the other sub-orders, principally by the absence of a labium sternale. It should be 

 emphasized that, in respect of the structure of the mouth, they differ more from Palpatores 

 than from Laniatores, although the mere outer form of their stomotheca recalls the Troguloidije 

 more than the other Opiliones. 



6. The Organs of Sense. 



A. The Eyes. The only real eyes found in Cyphophthalmi are those which previous writers 

 have described as " sessile eyes." Amongst the six genera with which we are acquainted the 

 only one which possesses eyes is Stylocellm ; the others are all blind, and this must also be 

 the case with " Siro" cypJwpselaphus Jos. (which vmdoubtedly must be transferred to another 

 genus), and with Miopsalis Thor., with which we are equally unacquainted, and in which 

 Thorell says that " sessile eyes " are not found. 



All species of the genus Stylocellus possess one pair of eyes, which must be considered small. 

 They are always placed widely apart, a short distance from the lateral margin of cephalothorax 

 (o in PI. I., fig. 1 d), and they are not placed on any protuberance, in which respect they differ 

 from those of the great majority of Opiliones. They are, so to say, placed as far backwards 

 as possible, as their position is above the coxae of the second pair of legs, and in Arachnida 

 the boundary between head and thorax lies precisely behind the second pair of legs. They 

 are but slightly convex, either circular or a little elliptical. As we are dealing with a group 

 of animals in which the majority of genera contain blind animals, we wish to affirm expressly 

 that these eyes are real eyes, witii a lens, not like those of Schizomus Simonis nob. belonging 

 to Tartarides, or of the genus Ghernes belonging to Chelonethi (Pseudoscorpiones), mere 

 eye-spots, that is to say, eyes in which the surface of the so-called lens is not perfectly 

 smooth, and which therefore can scarcely be supposed to be of use to the animals possessing 

 them for the purpose of real vision. 



In our estimation there can be no doubt that the two eyes which occur in Stylocellus 

 correspond moi-phologically to the pair of eyes met with in other Opiliones. This view is not 

 only supported by their number, but also by the circumstance that amongst Laniatores the 

 eyes are placed widely apart in Biantoidae and in the sub-family Stygnini proposed by Simon, 

 although even in these groups they are not placed so laterally as in Stylocelliis. 



In this connection we may mention those Opiliones other than Cyphophthalmi to which 

 more than one pair of eyes have been ascribed. According to Doleschall a species from India 

 belonging to Palpatores possesses three pairs of eyes, for which reason Thorell in 1876 (b,p. 114) 

 established the genus Hexonima for this species, on the authority of Doleschall ; but in 1891 



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