Mouth hi Laniatores and CyphophtJialmi 33 



iu Sabacon and Parasabacon tin.illy they are entirely absent. Sorenseu, the first author who 

 made a really careful study of the structure of the mouth in different Opiliones, denied (a, p. 509) 

 the existence of maxillary lobes of the second pair of coxa? in NemastomatoidiK and Troguloidse. 

 As they are found in all other groups of Opiliones, though in some cases being only rudimentary, 

 with the sole exception just mentioned, we have attentively investigated the question as regards 

 these two families, with the result that we have found no vestiges of them iu Nemastomatoidai, 

 but in those Troguloida? which we have examined, viz. Trogulus and Anelasmocephalus, they 

 exist in the shape of a pair of very small flat prolongations of the proximal extremities of 

 the coxcB (_ woodcut fig. F, lex-), quite incapable of movement. 



The mouth of Laniatores offers the following essential differences from that of Palpatores. 

 The maxillary lobes of the first pair of cox£e consist of only two parts, a distal one with 

 soft skin, and a proximal one, which is firmly chitinized, immovably joined to coxa, and 

 capable of being moved only with the latter, of which the movement is rather limited. In 

 many Laniatores the maxillary lobe makes a sharp angle with coxa, and may therefore be 

 described as clearly mai'ked off from it, but there are several others, for instance Cosmetoidse, 

 in which the maxillary lobe projects from coxa forming an even concavity, whereby the boundary 

 between the lobe and coxa is rendered less di.stinct. Labium steruale is joined to the maxillary 

 lobes of the first pair of coxae onlj^ at the very base ; it is always weakly chitinized, contrary 

 to what is the case with the other parts of the month, excepting the distal portion of the 

 maxillary lobes of the first pair of coxae. The maxillary lobes of the second pair of coxae 

 are never capable of movement ; in most of the families, for instance in Gonyleptoidas and 

 Cosmetoidae, they are not much developed and appear as low, rounded tubercles on the anterior 

 and interior corner of either coxa; but in several families, as in Tria^nonychoidaj and Biantoidae, 

 they are elongate and directed forwards and downwards ; wherever the}' project independently 

 they are sharply marked oft' from coxae'. 



The mouth of Cyphophthalmi has hitherto been but little studied, and the mandibles^ are 

 the only parts of it with regard to which authors may be said to agree. These (PI. 1, fig. 1 I; 

 PI. III., fig. 2/') have rather a downward direction, and their soft terminal portion is covered 

 with short pointed hairs which stand closer together on the interior surface than on the 

 others. In Purcellia the hairy covering is less dense, and the single hairs are at the same 

 time more rigid, almost spiniform (PI. IV., fig. 1 rjr). Such hairs also occur on the soft portions 

 of the other parts of the mouth ; their points are mostly turned backwards. 



Labrum (PI. I., fig. ] A and 1 i: PI. III., fig. 2/') consists of two parts, a proximal part, 

 clypeus, and a distal part, labrum proper. Clypeus (PI. I., figs. 1 h and 1 *', cl) is very short, 

 but broad, with a posterior prolongation (/p) on either side in the shape of a wing, to the 

 inner surface of which some of the musculi dilatatores of oesophagus are fixed. Frequently a 

 small chitinized piece extends from clypeus upwards between the bases of antennae. Labrum 

 pi'oper (PI. I., figs. 1 /( and 1 i, I) is i-ather broad just at the base, but the larger, anterior, 

 distal portion, which extends forward between the anterior portion of the mandibles, is so 

 much compressed from the sides that as a rule it is difficult or even impossible to see it on 



' Sorensen has stated that in these cases the maxillary Joseph (<i) under the name of maxillary pyramids, are the 



lobes of the second pair of coxie are movable ; but Thorell mandibles, though we do not quite unilerstand his description ; 



and Loman are right in maintaining that this is not so. nor have we been able to understand his description of the 



- There can be no doubt that the organs mentioned by other parts of the mouth. 



S. 5 



