Cephalothorax 5 



and " Hinterthorax " (pro-, inoso- and metathorax). In Palpatores the case is very different. 

 As regards Phalangioida:' the general ride must be said to be that the two segments which 

 in our opinion compose thorax in Araclmida are clearly delimitated by two transversal grooves. 

 Of these the anterior one is frequently less strongly marked than the posterior one, and 

 in Gagrella Stol.', as well as in the allied genera Melanopa Thor., Ceratobunus Thor. and 

 Zaleptiis Thor., the anterior groove is more or less indistinct. In "' Homalonutus' depressus Can., 

 which is nearly related to Sclerosoma, it is entirely obliterated. In Nemastoma lugubre O. F. 

 Miiller the limits of the two thoracic segments are visible as two fairly well-marked transversal 

 grooves, but they are only slightly marked in N. scahriculum E. S., N. Uliputanum Luc. and 

 N. argenteo-lunulattim E. S., and scarcely visible in iV. dentipalpe Auss. and N. gigas W. S. In 

 Tnigidtis Latr. it is impossible to distinguish the boundaries between the segments of cephalo- 

 thoiax, but in Metupoctea E. S., Anelasinocephalus E. S., Bicranolasma W. S. and Amopaiun 

 W. S., which all belong to Troguloidai, a slight transverse groove is visible which represents 

 the boundary between the two thoracic segments. In Ischyropsalis C. L. Koch, Simon has 

 already pointed out the existence of a cephalothoracic dorsal shield, on which a procurved 

 transverse groove, which does not quite reach the lateral border, is observable, and in the 

 majority of species also an abdominal dorsal shield formed by five tergites. It is, however, 

 to be noted that the anterior, cephalothoracic, dorsal shield does not comprise the whole of the 

 cephalothorax, but only the head and the dorsal arc of the anterior thoracic segment. That 

 such is the case is seen most clearly in I. MilUeri and Taracus Packardi E. S. In 

 /. MilUeri, where no abdominal dorsal shield is formed, as the tergites of the abdomen all 

 remain free, a separate, slightly chitinized plate is seen behind the cephalothoracic shield, and 

 in front of the abdominal tergites. This plate is very short, in the female as broad as the 

 cephalothoracic dorsal shield and much broader than the first abdominal tergite, whilst in 

 the male it is a little shorter and perhaps still more slightly chitinized and therefore somewhat 

 more difficult to discern. In Tamcus Packardi E. S. the abdominal dorsal shield consists of 

 five tergites, which coalesce completely, but nevertheless may be discerned (counted), each 

 of them bearing a couple of lightly coloured spots close to the lateral border. Between 

 the two shields a broad and rather long dorsal plate is situated, which is entirely free of 

 the anterior shield, but scarcely quite separate from the abdominal one. Inasmuch as the 

 number of tergites behind the plate just described is the same as the number usually found 

 in Palpatores, that plate cannot be anything else than the dorsal portion of the posterior 

 thoracic segment. In the females of the other species of Ischyropsalis with which we are 

 acquainted, viz. /. luteipes E. S., /. pyreinca E. S., /. dispar E. S. and I. Adamsii Can., there 

 is between the two dorsal shields a band of softer integument, rather long in the three first- 

 named species, but rather short in /. Adamsii, traversed by a fine sharjjly cut groove which 

 indicates the boundary line between two segments''', though the dorsal plate behind this 

 groove is so slightly chitinized that it does not appear distinct from the connecting membrane 

 behind it. In the male of /. dispar E. S. this soft belt is so short, that we have not 

 been able to discover the groove in question. In Sabacon paradoxus E. S., Parasabacon 



' In Gaiirella minax Thor., however, two boundary lines the Museum of Copenhagen, 

 of segments are clearly observable, of which the posterior - According to Simon's figure (i, PI. XXIV. fig. 4) a similar 



one as well as the limit between cephalothorax and abdomen groove occurs also in /. tiodifura E. S. $ , in which species 



are marked by rather broad bands of lighter colour, which the abdominal tergites are separate in the female, while a 



almost reach the lateral margins of the body, and consist of dorsal shield is said to exist in the male (v. Simon, ibid. 



a softer skin than the dorsal shields before and behind pp. 270 and 271). 

 them. The same is the case with several other Gagrellini in 



