14 Abdomen in Laniatores 



are well marked^ That it is the fourth which thus disappears is evident from the fact 

 of its being present, though slightly indicated, in congeners of the animal in question, in 

 which case the area behind it (the fourth tergite) always is much smaller than the pre- 

 ceding one. The area which is cut off by the last (fifth) groove is often very small, and 

 Sorensen (6, p. 126) did not consider that it represented a real tergite, but thought that 

 it was only the posterior margin (limbus posterior) of the dorsal shield. Thorell, on the 

 contrary, considered it to be a real tergite, and the justness of this view appears indisputably 

 from the fact that in some abnormally developed specimens of a still undescribed species, 

 where the posterior areae of the dorsal shield were separated from each other by strips 

 of soft skin, such an one was found also between " limbus posterior " and the preceding (fourth) 

 tergite. It will be seen that in all divisions of Laniatores, eight tergites can be accounted 

 for besides operculum anale. 



On the ventral surface Laniatores (with the exception already mentioned, of Oncopodoidse) 

 exhibit apparently only six sternites (woodcut fig. A'). Of these the " first " coalesces with 

 the fourth pair of coxa3, which are often very much expanded ; but the following sternites are 

 free. It is also worthy of attention that the following four sternites always are considerably 

 shorter, not only than the "first," but also than the last or "sixth," and that the latter almost 

 always exhibits a transverse impression or very shallow groove, which clearly indicates that it is 

 really formed by the coalescence of two sternites — a conclusion which is confirmed by the 

 fact, that each of the two parts separated by the said transverse groove generally carries 

 a row of granulations, just as is usually the case with each of the preceding four free 

 .sternites. On the " first " sternite a transverse groove is found behind the spiracles, in the 

 same place where the weaker transverse impression is found in Cyphophthalnii. This groove, 

 which extends nearly across the whole sternite, varies ver}' much as regards distinctness, 

 being sometimes very strongh' marked, in others less so, in others again scarcely visible. 

 The portion of the " first " sternite which is situated behind this groove shows almost always 

 a row of granulations, whilst these are scattered over the surface of the anterior part. Nor 

 can we doubt that this groove marks the boundary between two sternites. In this way 

 we are able to account for eight sternites in Laniatores, to begin with. In all Laniatores 

 the foremost sternite always Cannes at its anterior extremity a small operculum genitale 

 (?•), which is movable and always able to close the genital orifice completely. 



In Palpatores there are always eight clearly distinguishable tergites besides operculum 

 anale. Except in Ischyropsalidoidae^ and the Gagrellini above mentioned^ at least^ the five 

 first tergites of abdomen are fused with the upper surface of cephalothorax so as to form a dorsal 

 shield, whilst as a rule the three posterior ones besides operculum anale are free. In 

 Troguloida", Nemastomatoidse, and Sclerosoma Luc. with allied genera (Sclerosoniatini E. S.), 

 all of which comprise species with hard integuments, the three posterior tergites (besides 

 operculum anale) are always free\ In Plialangium and allied genera, of which the majority 

 of species have more or less soft integuments, the three posterior tergites, besides operculum 



1 The family Pachyloidse W. S. which for this reason salis and Nemastoma four to five free tergites are met with 



was separated from Gonjleptoidffi cannot therefore be main- (counting operculum anale as an independent tergite) is not 



tained as such. correct. 



- See above, pp. 5 — 6. ^ It is an error when Thorell states («, pp. 465 — i67) that 



■' See above, jj. H, note 1. two to four dorsal plates are free in Scleromimt, Truriiilus 



■* Thorell's statement (<(, pp. 46.5 — 467) that in Ischyrop- and Anelasmocephalus. 



