NO, 10 KliEUING OUCAXS OF AKAellMUA — SNOUeiKASS 69 



hy a lonp^ duplicature of tlie prosotiiatic dorsuin (H). The chcliccrac 

 (Chi), in tlic retracted state, arc invagiiiated far into the body from 

 between the tectum {Tcct) above and the epistome {Ilpst) below. 

 Accorchnc; to Thon the chebccrae are five-segmented, but since he says 

 only two joints are articulations, it is evident that they are really 

 three-segmented. The anterior parts of the cheliceral sheaths (aChS) 

 arc double tubular folds. The fold forming each outer .sheath is ex- 

 tended dorsally from the tectum (Tcct) and ventrally from the base 

 of the epistome (Epst) to the end of the cheliceral shaft, where it 

 is invaginated into itself to form the inner sheath more closely in- 

 vesting the chelicera and attached to the latter on the end of the basal 

 segment. Thon describes also posterior cheliceral .sheaths ( I», pChS) 

 reflected dorsally from the inner part of the tectum and ventrally from 

 the epistome; but a posterior enshcathment of this kind is difficult to 

 understand morphologically, and Thon, himself, says it probably 

 results from some secondary modification. 



The long epistomal plate of Ilolothyrus ( hg. 24 !•, lipst), called 

 "labruni" by Thon. underlies the cheliceral sheaths and gives attach- 

 ineni to tiie dorsal muscles of the pharynx (E, F. Phy) ; laterally it 

 is united with the mesal walls of the pedipalp coxae (IC, IICx). 

 Distally the epistome bears a small spiny lnl)e (I'l. Lm) overhanging 

 the mouth (Mtli). The interior of the lobe is filled with radiating 

 columns of fibrous tissue, and the organ is provided with a pair of 

 depressor nuiscles arising on the epistome. This movable, spine- 

 covered lobe evidently has a rasping function, and for this reason 

 Thon calls it the "Radularorgan" : there can be no question, however, 

 that it is the lalirum in an unusual form. 



The lower wall of the capitulum of Ilolothyrus (fig. 24 D) has a 

 three-lobcd apj^earance owing to lengthwise indentations along the 

 sides (E, V). Anteriorly the coxal cavity is divided into three com- 

 partments by partitions (E, />) inflected from the margins of the 

 epistome to the coxal grooves, but posteriorly the partitions are absent 

 (F). The distal end, or hypostomal region, of the ventral wall of the 

 capitulum (D. list) bears a pair of broad median lobes and a pair of 

 small lateral processes suggestive of the four apical ap[>enflages in the 

 Xotostigmata. The relatively long palps ( 1). /7/») arc five-segmented 

 but appear to lack pretarsal claws. 



Ganiasidcs.— The capitulum is .said by Winkler (1886) to be well 

 developed in all I'arasitidae. but ventrally the .segment of the first legs 

 closely adjoins the capitulum (fig. 25 A. B) and projects with it from 

 the anterior cavity of the body. .\ bifid ventral process (/) arises 

 from the tritosternal region as in Xotostigmata. The cheliccrac arc 



