250 E. I. Pocock — A New Carboniferous Arachnid. 



from the drawing, is plainly visible thvougli the eighth segment, 

 near its anterior border. 



The principal measurements in millimetres of the type-specimen are 

 as follows : — Total length 21, length of carapace 6, width 7 (approx.) ; 

 length of abdomen 15 ; greatest width 10; width in front 6-5. 



The characters enumerated above, though proving incontestably 

 the right of the species to a place amongst the Anthracomarti 

 near Eophrynus and Kreischeria, show no less clearly the impossi- 

 bility of associating it with either of these genera. And since it is 

 not intermediate between these or any two genera known, but differs 

 strikingly from all in certain well-marked features, it becomes 

 necessary to erect a new genus for its reception. This I propose 

 to name and diagnose as follows : — 



Gen. Anthracosiko, nov. 



Carapace and appendages of prosoma constructed apparently as in 

 Eophrynus, having the posterior horizontal area and the median 

 impression short. Opisthosoma consisting of eight tergal plates on 

 its upper surface, as in Kreischeria, but the anterior and posterior 

 border of all the plates transverse and subparallel, and not becoming 

 progressively more and more recurved towards the hinder end of the 

 body, as in Eophrynus, Kreischeria, etc. All the lateral laminae 

 directed obliquely outwards and backwards : those of the anterior 

 segments in the form of narrow sclerites, overlapped externally by 

 the chitinised subjacent integument ; those of the posterior segments 

 large. In Kreischeria and JEophrynus all the laminse are large and 

 subsimilar in size and shape. 



The generic name for this Arachnid is suggested by the geological 

 formation in which the fossil was found, and by its affinity, remote 

 though it be, to the existing Opilionid genus 8iro. 



The typical and only known species of this genus I propose to 

 name Anthracosiro looodwardi, sp.n., dedicating it to Dr. Henry 

 Woodward, F.R.S., as a slight tribute to his valuable contributions 

 to our knowledge of fossil Arthropoda. The specific characters of 

 this species are enumerated with sufficient detail in the description 

 of the specimen already given. 



2. Further remarJcs upon the morphology of the Anthracomarti. 

 While working out this new Arachnid, I examined a cast of 

 Eophrynus prestvicii, which I did not see previous to the publication 

 of the description of this fossil in the Geological Magazine for 

 October and November of last year. In this cast I notice one little 

 structural point, of some morphological importance, which was not 

 sufficiently defined in the others to allow me to speak with assurance 

 about it. With reference to the anal plate, I said (p. 447) : " This 

 plate has the form of a transversely oval tubercle, and in one of the 

 casts is marked by an incomplete transverse groove which suggests 

 the possibility of its consisting of distinct sternal and tergal elements. 

 If this be the case, the anal somite will resemble that of the Ambly- 

 pygous Pedipalpi [Phrynidse], rather than that of the Cyphoph- 

 thalmous Opiliones." This groove is so strongly defined in the new 



