140 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Dec. 17, 



24, or more branches, each with a single row of cells — not a double 

 row as supposed by Prof. Hall, who must have seen the ends of the 

 cells crushed vertically upon the narrow stipes. 



Tetragrapsus, gen. nov. Figs. 8a, 8 b. 



Fronds twice dichotomous near the base, of simple, long-celled 

 stipes ; the base of the branches not connected by a corneous plate 

 (the branches sometimes patent, sometimes closely reflected : M'Coy, 

 in Uteris). 



Phtllograpttjs, Hall. Figs. 7 a, 7 b. 



There are two species of this beautiful genus in the slates ; but I 

 prefer to leave the description of them open for the present. Prof. 

 Wyville Thomson is hard at work on this group, and it is a pleasure 

 to put good materials in the hands of so good a naturalist. 



Two of the most remarkable of these Graptolites (see figures 8 

 and 13) were drawn from specimens in the collection of Mr. W. 

 West, of Wimpole Street. I refer specially to the rare Tetragrapsus 

 cruciah's, and the Didymograpsus marked e, fig. 13, which is exceed- 

 ingly like I). Pantoni, M'Coy, from Victoria. I have called it D. 

 V-fraetus. In truth, no one can collect in this region without 

 doing some good ; for the Skiddaw slate is the metropolis of the 

 Graptolites. 



2. On Fossil Estherije and their Distribution. By T. Rupert Jones, 

 Esq., F.G.S., Professor of Geology and Mineralogy at the Royal 

 Military College, Sandhurst. 



Introduction. — In 1856* I offered to the Society some remarks on the 

 probably Crustacean character of the little fossil that used to be termed 

 Posldonomya minuta, on its Estherian relationship, and on some points 

 in the geological distribution of Estheriaf. Much of the material that 

 I have used for my ' Monograph of Fossil Estheriae,' published by the 

 Palaeontographical Society, was then in my hands, but much informa- 

 tion and very many specimens have been contributed since by friends, 

 abroad and at home, so that I am now enabled to recognize fourteen 

 fossil species, with several varieties. These are from the freshwater 

 or brackish- water deposits of the Devonian, Lower and Upper Car- 

 boniferous, Permian, Triassic, Rhsetic, Oolitic, "Wealden, and Tertiary 

 formations. 



Though often imbedded in shales or marls in close proximity to 

 other beds containing truly marine organisms, and even near beds 

 impressed with casts of salt- crystals, yet the fossil Esiherice have 



* Quart. Journ. G-eol. Soc. vol. xii. p. 376. 



t In this paper Estheria was erroneously referred to as a marine Crustacean ; 

 and a mistake was made in the allusion to a Silurian Nummulite. The lime- 

 stone containing this Nummulite is Carboniferous ; but, coming from a Silurian 

 district in Shropshire, it was at first mistaken for Aymestry limestone. 



