74 " Derivation " of Gihocellmn 



placed the sexual orifice of GiboceUum close to the base of the abdomen, could of course not 

 locate the four spinning mamillse in front of it, but placed them behind the orifice, and 

 in a depression, as also should be the case in Obisium and Chthonius. At the same time 

 he seems to have been doubtful as to where best to place the mamillse iu GiboceUum, 

 because according to the text (b, pp. 294 and 328) they were to be found on the second 

 abdominal sternite', but according to PL XX., fig. 1, their place was on the first sternite. 

 The external form and structure of the mamillae, as well as of the spinning glands, he 

 stated to agree with those parts in Aranese. 



A very striking feature — according to Stecker's own showing — in the composition of 

 GiboceUum is the intestinal canal, which is very remarkable for an Arachnidan : it is said not 

 to be furnished with cceca (b, p. 323) "as in the Aranese, Galeodes, etc." but it exhibits irregular 

 expansions which "thus are to be looked on as a homologue of the coeca possessed by 

 other spiders " (b, p. 324). Besides this the intestinal canal is sinuate {b, p. 325). That is 

 not the case in any other Arachnidan, a circumstance which, however, the author does 

 not mention. 



Still more remarkable are the Malpighian tubes which Stecker himself describes as 

 " peculiarly developed " (b, p. 328), because, says he, " at about the middle of their course 

 they are subdivided into numerous narrow small tubes, which, however, again unite by degrees 

 into larger and larger tubes, until at last they reappear as simple canals forming loops." 

 The representation of this portion of the Malpighian tubes on PI. XIX. looks more like the 

 capillary network in a vertebrate than any organ known to us in any Condylopodan. In 

 Phalangium the Malpighian tubes were recognized as such for the first time by Plateau, 

 whose treatise only appeared in 1876, that is in the same year as Stecker's second paper 

 on GiboceUum. 



It was, as already stated, from Siro {Cyphophthalmus) that Stecker borrowed the external 

 features of his GiboceUum, the number of abdominal segments, the structure of the limbs and 

 the eyes, though in this last matter he was not very careful. On Joseph's figure of Cyphoph- 

 thalmus duricorius Jos. the oi-gans which he mistook for eyes are quite correctly placed above 

 the interspace between the second and the third pairs of legs ; but in Stecker's second paper, the 

 first pair of eyes are placed a little in front of the first pair of legs, whilst the second pair are 

 seen a little behind the same. Although the posterior pair of eyes in GiboceUum are thus 

 placed considerably further forward than the so-called eyes in Cyphophthalmus, the position 

 of the eyes relativelj' to the above-mentioned " roll-like elevation " shows that it is the posterior 

 pair of eyes that have been acquired for GiboceUum. 



Joseph's account of the structure of the mouth in Cyphophthalmus duricorius was neither 

 good nor very intelligible, and therefore Stecker could not understand it (a, p. 236; b, pp. 308, 309). 

 Accordingly he " decided " not to sacrifice any of his twelve specimens to an examination of 

 the mouth of GiboceUum, " because," says he, " I was chiefly anxious to obtain a clear idea of 

 the internal anatomy." This much, however, was clear enough from Joseph's account, that in 

 Cyphophthalmus the basal joints of the palpigerous limbs have the oral orifice between and 

 behind them, and accordingly Stecker tells us that (b, PI. XVII., fig. 2) the mouth in 

 GiboceUum is situated behind the basal joints of the palpigerous limbs. 



' At the same time Stecker says in another place (p. 300) ; segments appeal's to me to correspond to the spinning orifice 

 " An orifice between the second and the third abdominal observed by me in Chelonethi." 



