120 Mr. J. Blackvvall on newly discovered species of Araneidea. 



closely allied to Bithynia, but the operculum is that of Littorina, 

 and the animal resembles Paludinella ulvce. 



"2nd July. — I again visited the Greenwich marshes yesterday 

 for the purpose of ascertaining the range of Littorina (?) anatina 

 and Assiminia Grayana, and to inform you more particularly of 

 their respective habitats. I found both of them more or less 

 distributed along the banks of the Thames, from a little below 

 Greenwich Hospital to the upper Pier at Woolwich, a distance of 

 about three miles. .. I met with them occasionally in the same 

 localities^ but their habitats are somewhat different. The Litto- 

 rina inhabits muddy ditches and their banks, and it is gre- 

 garious. The other molhisk inhabits muddy places, but seldom 

 occurs under water. It is in countless profusion at and about 

 the roots of the water-flag, and is more generally dispersed than 

 L. (?) anatina. It is associated with Limneus palustris (our 

 tinctus) and L. truncatulus. The Littorina lives in company 

 with Bithynia impura and Leachii, as well as with the Assiminia. 

 I have little doubt that both kinds are also to be found on the 

 other side of the river in the Isle of Bogs, and perhaps below 

 Woolwich. The Assiminia has the same habit as Paludinella 

 ulva, and seems to take its place on the brackish estuary of the 

 Thames. 



" I remain, my dear Sir, yours sincerely, 



"J. Gwyn Jeffreys.^' 



" Win. Clark, Esq., 

 Exmouth, Devon." 



I am. Gentlemen, 



Your most obedient servant, 



William Clark. 



XI. — Descriptions of two newly discovered species o/" Araneidea. 

 By John Blackwall, F.L.S. 



Tribe OCTONOCULINA. 



Family Ciniflonid^. 



Genus Ciniflo, Black w. 



Ciniflo humilis. 



Length of the female y yth of an inch ; length of the ecphalo- 

 thorax ^'^ ; breadth y^j ; bi'cadth of the abdomen ^-^ ; length of 

 an anterior leg ^ ; length of a leg of the third pair yj. 



The four intermediate eyes describe a trapezoid, the two ante- 

 rior ones, which form its shortest side, being much the smallest 



