and Classification cf the OpUlones. 511 



Part II. — The Position and Classification of the 



Il^SIDIATORES. 



Up to 1900 tliere was a tacitly admitted or openly expressed 

 agreement that the Opiliones, apart from tlie Anepignathi or 

 C^'pliophthalmi, fall into two nicely balanced groups — the 

 Palpatores or Plagiostethi and tiie Laniatores or Mecostethi. 

 In the year named this arrangement was disturbed by 

 Dr. J. C. C. Loman (Zool. Jahrb., Syst. xiii. p. 80), who 

 proposed the suborder Insidiatores for the family Triseno- 

 nychidai of Sorensen — a family resembling the Laniatores in 

 all essential diameters except the ))resence of a single claw on 

 the tai'si of the fifth and sixth pairs of appendages, as in the 

 Palpatores. The characters in which the Palpatores differ 

 from the Laniatores are numerous and have been pointed out 

 by Thorell, Simon^ and especially Sorensen. In Loman's 

 opinion the systematic value assignable to the claws is equal 

 to that of all the other structural characters combined. In 

 the present year (Zool. Jahrb. xvi. pp. 170-171) he tabulates 

 the characters of the tiiree suborders, and adds to his earlier 

 diagnosis of the Insidiatores two additional features in which 

 they resemble the Palpatores and differ from the Laniatores — 

 namely, the presence of two reccptacula semmis in the female 

 and of an erectile muscle for the glans of the penis in the 

 male. Judging, however, from his tabulation of the cha- 

 racters, the Insidiatores are at one with the Laniatores in the 

 segmentation of the opisthosoraa, the structure of the palpi, 

 of the coxje of the appendages, and of the sternum of the 

 prosoma, in the wide distance between the mouth and genital 

 orifice, in the number of the saccular diverticula of the 

 alimentary canal, the structure of the lubricating-glands of 

 the penis, and the structure of the ovipositor. 



It appears to me that a greater value must be assigned to 

 these many points of resemblance than to the three points of 

 difference above alluded to, and that the Triienonychida^ or 

 Insidiatores n.ust still be classified with the Laniatores in a 

 group equivalent to the Palpatores. Nevertheless it is evident 

 that they differ from the remaining families of Laniatores in 

 characters of greater importance than those used to distinguish 

 tiiese said families from each other. Hence it is perhaps 

 advisable to accept the Insidiatores as a group equivalent to 

 the Laniatores, and to classify them together under the 

 Mecostethi. I propose therefore the following classification 

 of the Opiliones : — 



