6 Cephalothorax 



(" Nemastoma ") crassipalpis L. Koch and Tomicovieras hispinosiis Pav., which are all nearly 

 allied to Ischyropsalis, the same structure is found in all essential points. There is a separate 

 cephalothoracic dorsal shield with a transverse groove, and between this shield and abdomen, 

 which in all these species is rather soft, a dorsal plate is found which carries a couple of 

 fine spines, and is of the same length and consistency as the abdominal tergites. On the 

 original specimen of Parasabacon crassipaljns (L. Koch) and in those of Tomicomeriis hispinosus 

 Pav. the abdominal tergites are difficult to count, but in Sabacon paradoxus it is easy to 

 count them and thus to convince oneself that the plate in question is here really the 

 posterior dorsal segment of cephalothorax. Considering further that this plate in all these 

 three nearly related forms is equipped with a pair of fine spines, as already mentioned, it 

 is evident that in Par-asabacon crassipalpis and in Tomicomerus, it belongs likewise to 

 cephalothorax and not to abdomen'. Although this structure is not without a parallel else- 

 where, viz. in Gacp-ella minax and allied s^jecies-, it must nevertheless be regarded as very 

 characteristic of Iscliyropsalis, Taracus, Tomicomerus, Sabacon and Parasabacon. 



As regards Cyjahophthalmi, it has never been doubted that the boundary between 

 cephalothora.K and abdomen is indicated by the foremost of the straight (or almost straight) 

 grooves on the dorsal shield, opposite the extremities of which groove the body is a little 

 contracted. In front of this straight groove another is visible which is strongly curved, our 

 sulcus posterior cephalothoracis (several figures on Pis. I. — V.), and points on either side to 

 the space between the third and fourth pair of coxse. That this groove, which is absent 

 only in Parasiro corsicus E. S. (PI. V., fig. 2 a), really forms the boundary between the two 

 thoracic segments cannot be doubted, partly because of its position and partly because it is 

 known from Phalangioidas that the foremost of the two segmental boundaries is the first 

 to disappear. In several forms the lateral portions of the posterior thoracic segment are 

 marked off from the middle portion bj^ an impression which is more or less distinct in the 

 species of Stylocellus (PL I., fig. Id) and particularly marked in Pettalus brevicauda Pock. 

 (PI. III., fig. 3 a). In Purcellia (PI. IV., fig. 1 a) this segment is the broadest portion of 

 the whole body, but generally the greatest width is found across the second or (in Pettalus 

 brevicauda) the third tergal plate of abdomen. 



In front the cephalothorax is more or less rounded downwards, but the anterior extremity 

 projects in the middle beyond the base of the antennte (chelicerse) forming a prominent 

 collar, which is well developed in Stylocellus (PI. I., fig. I d, c), Ogovia and Pettalus, but 

 smaller in Purcellia, Siro and Parasiro. The anterior part of the sides of cephalothorax 

 are at the same time generally somewhat concave, and thus a broad, rounded, longi- 

 tudinal ridge is formed which anteriorly occupies the middle of the body, and in front 

 terminates in the collar, where generally it is expanded in the shape of a triangle. In 

 Laniatores we are not aware of anything corresponding to this collar, because the " limbus 

 anterior," as we call it, which often occurs on the dorsal shield does not, in our opinion, 

 correspond to it. But we believe that this collar is represented in Palpatores by that 

 piece or those pieces which are often found in the membranaceous part above the base of 



' Pavesi describes the segment which carries the pair of salidoid* must be united on account of Tomicomerus. We 



spines from which he has named the species, as the first place Tomicomerus between Tamcus and Sahacon. We may 



abdominal, a view which is very natural in the absence of a add that through the courtesy of Professor Emery we have 



comparative study of the question. We would take this early been able to examine the original specimens described by 



opportunity of emphasizing that we cannot share the opinion Pavesi. 

 of Pavesi, that the families Nemastomatoidse and Ischyrop- ^ See above, p. 5, note 1. 



