and Classification of the Oplliones. 515 



tores the second and third are fused, tliough the line between 

 the two is very deep and strong in some forms (e. g., Biantes). 



In the Eupagosternous Palpatores the divisional line 

 between the second and third is feebly {Dicranolasma) or 

 not at all (Trogulus) marked, and tiie eighth is small. 



In all the Apagosternous Pali)atore.s, except Taracus be- 

 longing to the Ischyropsalidse, the eighth is suppressed, the 

 anal tergite closing against the postei-ior border of the seventh. 

 Similarly in all the members of this group the first or genital 

 is not or scarcely differentiated from the second, and only in 

 some cases (e. g., Sclerosoma) is there a deep groove between 

 the second and third. Hence in the Phalangioid Palpatores 

 the number of sternites may be reduced to six, (1) by tl>e 

 suppression of the eighth (anal) and fusion of the fii-.st 

 (genital) with the second (tracheal) in Sclet'osoma] (2j by 

 the fusion of the first, second, and third into a single plate in 

 Taracus, or even to five by the fusion of the first, seciuid, and 

 third, and thesuppressionof the eighth, as in most Phalangiinaj. 



Finally, in many genera of Laniatores the eighth shows 

 indications of being composed of two sternites, which would 

 bring the total number of sternites up to nine, thus equalling 

 the tergites in number and agreeing precisely with the 

 number of sternites found in the young of Pettalus and the 

 adults of the species of SfyloceUus {LeptopsaUs) amongst the 

 Anepignathi (Cyphophthalmi), the third suborder into which 

 the existing Oi)iliones fall, and also with the numbers found 

 in the genera of the Carboniferous Anthracomarti, as I have 

 recently shown (Geol. Mag. 1902, Oct. and Nov.). 



EXPLANATION OF PLATES IX. & X. 



Fig. 1. The ventral surface of the prosoma of a species of Gagrella (1 A) 

 one of the Phalangiidse, and of Ischyroj-'Salis (1 Bj, one of the 

 Ischyropsalidaj, with the genital prolongation of the opistho- 

 soma removed, to illustrate the structure of the sternal plates 

 &c. in the Apagosterni. II-VI, basal segments of the ap- 

 pendages from the second to the sixth pairs ; m.c. 2, 7n.v. 8 m.v. 4 

 maxillary processes of the second, third, and fourth appendages • 

 St. 1, anterior sternal plate or labium ; st. 2, posterior sternal 

 plate, the so-called sternum proper ; tnb., membrane forming the 

 roof of the genital canal, representing, perhaps, the sternal'^area 

 of the genital somite. 



JVy. 2. Ventral sui-face of the prosoma of a species of Nemastoma, one of 

 the Eupagosterni, with the genital prolongation of the opistljo- 

 soma removed. I-VI, basal segments of the appendages ; Ir. 

 labrum ; mx. 2, m.i: 3, maxillary processes of second and third 

 pairs of appendages ; sf., sternal plate attached anteriorly to tl.e 

 piriform labium ; yjib., membrane forming the roof of the 

 genital canal, and representing, perhap>, the sternal area of the 

 genital somite. 



