Abdomen in Cjiphoplitlialmi 11 



reach up to the "sixth" sternite. The "seventh" sternite is never movably connected with 

 the "sixth." Generally the boundary between them is marked hy a distinct groove (in Stylocellus 

 and Purceliia $ ), but in some cases (in Pettalus. Purcellia ^ and in Parusiro) this groove 

 is difficult to see or even obliterated in the middle, while plainly visible at the sides. In 

 Siro (PI. v., fig. 1 I) the " sixth " and " seventh " sternites are almost fused into one, the 

 groove being almost entirely invisible even at the sides ; at the .same time tiie grooves 

 indicating the boundaries between the ninth tergite and these two sternites are so slightly 

 marked in this genus that it is very difficult to recognize them. As it was only through 

 previous study of other genera, that it became possible to di.scover or understand the true 

 structure in Siro, and as it is sufficiently difficult to recognize it in Parasiro, it is easily 

 understood that authors, who were acquainted only with one or both of these genera, have 

 fallen into mistakes as to the number of tergites and sternites in these small animals^ Of 

 Offovia we have had only one and that a unique specimen before us, which we were enabled 

 to inspect b}' the kindness of M. E. Simon, and which we could not, therefore, dissect ; but 

 as the result of a careful examination of the exterior, we believe ourselves justified in 

 saying that it agrees entirely with Siro in this point, that the " sixth " and " seventh " 

 sternites are at the sides almost entirely united to the ninth tergite ; and it is only on 

 one side that we believe ourselves to have seen a vestige of the groove dividing the two 

 sternites (PI. III., fig. 1 e). 



The " fifth " sternite is always movably connected with the " sixth " and the " fourth," but 

 the " first," " second," " third," and " fourth " sternites are united so as to form a ventral shield, 

 the boundaries between them being marked by transverse grooves (PI. I., fig. 16; PI. II., 

 fig. 6 a; PL III., fig. 2b; PL IV., fig. 16; PL V., fig. 1 b). Upon the whole the sternites 

 increase in size forwards, but the " first " is disproportionately larger than any of the others. 

 On this sternite a pair of curved grooves are discernible behind the spiracles, our " sulci 

 laterales obliqui" (PL I., fig. 1 b, t), each of which commences at the lateral margin of 

 the body and sweeps round the spiracle inside of it. There can be no doubt that this 

 " first " sternite is formed by the coalescence of two or three, as already Thorell thought 

 (c, p. 26), but we prefer to leave the question, where the limits between the united seg- 

 ments are to be located, open for the present, because in the young Stylocellus sulcatus, 

 n. sp. (PL II., fig. 3 h), and also in the young Purcellia illustrans (PL III., fig. 4 c), we have 

 noticed that two small areje in which the spiracles are situated are separated from the rest 

 of the " first " stei-nite by a groove in which the integument is quite soft, whilst sulci 

 laterales obliqui in the young Pettalus brevicauda Pock, are very plainly connected with each 

 other by a groove extending across the " first " sternite. 



In Cyphophthalmi, as in Opiliones generally, abdomen extends forwards on the ventral 

 side into the space between the coxae on either side. The " first " sternite is anteriorly 

 prolonged into a plate of varying shape, "operculum genitale " (PL I., fig. 1 b. and r in 

 figs. 1 I and 1 m), which in all other Opiliones is movably connected with the main part 

 of the '• first " sternite, but in Cyphophthalmi is immovable ; at the utmost it is separated 

 from the rest of the " first " sternite by a suture. Nor does operculum genitale ever close 

 the genital orifice in Cyphophthalmi, in which respect this sub-order differs from the other 

 sub-orders of Opiliones. The remaining part of the frame round the genital orifice, our 



' Thus Simon (b, p. 143) and Sorensen (d, p. .5-59) counted eifiht tergites and six (clearly distinguishable) sternites. 

 Joseph on the contrary (6, p. 270) counted eight of each. 



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