Mr. J. Black wall on neivli/ discovered species 0/ Araneidea. 173 



five ocular plates are small and heart-shaped, their apex is di- 

 rected towards the anal opening, and their base to the area ; the 

 madreporiform tubercle is slightly elevated on the single ovarial 

 plate, and the surface of the discal plates is almost destitute of 

 sculpture or granulation. 



Affinities ami differences. — D. Mooreii resembles D. depressum, 

 Ag., in the depression of its upper surface and the flatness of its 

 base, likewise in having the tubercles of both areas of nearly a 

 uniform size around the base ; but it is readily distinguished 

 from D. depressum by the number and greater development of the 

 tubercles of the ambulacra, which maintain their size throughout ; 

 whilst in D. Mooreii the ambulacral tubercles ai-e fewer in num- 

 ber and rudimentary in size in all the upper part of the areas. 

 The contour of the test moreover does not assume the penta- 

 gonal outline of D. depressum, nor has the upper surface of the 

 interambulacral areas the median depression seen on the test of 

 the latter. The mouth-opening is larger, and the decagonal 

 lobes are more equal in size in D. Mooreii than in D. depressum. 



Locality and strutiyraphical range.- -V^^e have collected D. 

 Mooreii in the Upper Lias of Gloucestershire. Mr. Moore found 

 it in the same stratum near Ilminster with Ammonites communis 

 and A. serpentinus. Professor Deslongchamps has communicated 

 a specimen of this Urchin which he found in the Lias superieure 

 of May, Calvados, associated with Leptana Davidsonii and The- 

 cidea Bouchardii and several other species. 



We dedicate this species to Mr. Moore, of Ilminstei*, whose 

 assiduous researches have brought to light so many interesting 

 forms from the Upper Liassic beds of Somersetshire. 



[To be continued.] 



XVII. — Descriptions of some newly discovered species of 

 Araneidea. By John Blackwall, F.L.S. 



Tribe OCTONOCULINA. 



Family Salticid.*;. 



Genus Salticus, Lair. 



Salticus promptus. 



Length of an immature female /^ths of an inch ; length of 

 the cephalo-thorax ^'^ ; breadth ^\ ; breadth of the abdomen 

 7j'^ ; length of a posterior leg j\j ; length of a leg of the second 

 pair j\. 



The cephalo-thorax is large, glossy, nearly quadrilateral, ab- 



