Alimentarij Canal 47 



Laniatores Sorensen {b, pp. IfiT, 168) found four pairs of diverticula, afterwards Louian (a, p. 36) 

 found four pairs in Phalaii<,noid;e, and we can conKrni his statement'. We have found the 

 same number in Cypliophtlialnii {Sti/locellus and Pnrcellia) as also in a species of Trogulus, 

 which we dissected on purpose. This number may therefore be considered characteristic 

 of the whole order. In Cyphophthalmi the diverticula are quite without branches. The 

 figures 1 s and 1 i on PI. I. show the position of the diverticula (di) in an animal 

 in which the two anterior pairs had been ruptured by the opening of the body, close to 

 their rise from the alimentary canal. The first pair is as usual the shortest and is confined 

 to the dorsal surface of the alimentary canal, where each of them forms a short but abruptly 

 bent curve. The second pair winds round to the under surface of the alimentary canal, 

 passing under the first pair ; the third and fourth pairs (di^ and di*) are essentially confined to 

 the dorsal surface, though the third pair also envelops the canal a little from the sides. According 

 to Treviranus, Tulk and Plateau diverticula in Phalaugioidee are divided into a great 

 number of lateral lobes, and as Sorensen found that the two anterior pairs in Laniatores 

 are undivided, and the last two pairs subdivided only once, he {d, pp. 575 — 57.9) thought 

 that this point of structure might offer a distinguishing character between Palpatores and 

 Laniatores. But our investigation of Trogulus rostratus has shown us that this does not 

 hold good. Of the four pairs of very slender diverticula found in that species the two 

 first pairs are undivided and proportionally short, whilst the two posterior pairs are only 

 a little branched, but so extremely long that their length much exceeds that of the whole 

 alimentary canal ; they form large loops, particularly on the dorsal surface of the latter, so as 

 to produce an appearance which reminds us of the surface of the cerebrum in a mammalian. 

 Since this was written Loman {g, p. 171) has briefly stated that also amongst Laniatores he 

 has found the diverticula (? all) to bo branched in some forms; unfortunately he does not 

 give the names of these forms. 



o 



Several authors have .said that the diverticula which branch off from the mid-gut of 

 the alimentary canal in many Arachnida, serve for the reception of food. This, however, 

 appears to us very doubtful, and as regards Opiliones we may affirm with certainty that 

 it is not the case. The middle and anal divisions of the alimentary canal may be found 

 quite filled with more or less digested portions of food, fragments of animals which are 

 easily recognized by the broken pieces of chitine which are contained in them ; but such 

 are never found in the diverticula, as indeed Tulk and Plateau (p. 15) have already pointed 

 out as regards Phalangium, and Sorensen as regards Laniatores. The last-named writer 

 says (b, p. 170) that diverticula " are found distended just when the alimentary canal is 

 empty of food, after the animal has been fasting through a couple of weeks." 



10. Organs of Excretion. 



As we are unable to give a satisfactory account in all respects of the excretory organs 

 in Cyphophthalmi, we prefer first to mention the structure in the other sub-orders of 

 Opiliones. Both Treviranus and Tulk observed only some loops of the organs of excretion and 

 therefore misinterpreted them. Treviranus described them as " Gallengefiisse," biliary ducts, 



1 Plateau had already before indicated three pairs of be noted, however, that what these two authors refer to is 

 diverticiila in Phalangioida; ; afterwards Eossler concluded not, strictly speakinj,', the number of diverticula, but the 

 (p. 676j that there were six pairs in these animals. It should number of their openings into the alimentary canal. 



