1853.] SHARPE SANDS AND GRAVELS OF FARRINGDON. 195 



viz. Manon pesisa, M. marginatum, M. macropora, or M. Farring^ 

 donense. 



Verticillipora anastomosans, Mantell. Pl. V. fig. 1. 



V. sessilis, ramosa, e fibris dense reticulatis composita : ramis tubulosis, 

 cylindricis, liberis vel coalescentibus, subsequalibus ; intus tubo eentrali 

 septisque horizontalibus numerosis mimitis : tubo supenie aperto, intus 

 poris coneeiitricis j^erforato. 



An attached branching sponge ; with cyUndrical branches of nearly 

 equal diameter, formed of a thin external wall connected to a small 

 central tube by numerous horizontal diaphragms ; the whole consist- 

 ing of uniform, closely reticulated, fibrous tissue ; the central tube 

 is open at the top of the branch, and is furnished at irregular .inter- 

 vals with a circle of openings into the outer chambers. The branches 

 are marked by numerous slight constrictions, and coalesce when 

 growing in contact. 



Forms irregular clusters of 2 or 3 inches across ; the branches 

 vary from ^th to ^ an inch in diameter, but are usually of about ^ of 

 an inch. The diameter of the central tube is very nearly a quarter 

 of the diameter of the branch. 



I venture to offer a description and figures of this curious sponge, 

 which is the most interesting of all the organic remains found at 

 Farringdon ; as Dr. Mantell' s woodcuts hardly do justice to its com- 

 plicated structure. It is one of the most abundant species found at 

 Farringdon, but has not yet been recognized elsewhere. 



Plate V. fig. 1 a. A branching specimen, with two of the hranches 

 coalescing. 



Fig. 1 b. Exterior of a branch. 



Fig. 1 c. Top of the same. 



Fig. 1 d. Horizontal section. 



Fig. 1 e & If. Perpendicular sections : a a, the openings from the 

 tube into the chamber. 



Fig. 1 g. Portion of the surface magnified. 



Manon macropora, Sharpe. Pl. V. figs. 3 & 4. 



M. sessile, expansunivelcyathiforme; extus fibrosum, intus membranaceum ; 

 osculis majiusculis, inaequalibus, concentricis, sub-stellatis ; canalibus 

 sex vel octo ab osculis divergentibus. 



A sponge attached at its base, and either irregularly cup-shaped 

 or expanded, consisting of a loose fibrous network, which is covered 

 on the inner side by a membrane pierced by large round openings 

 arranged in concentric rings, and varying in size and distance from 

 each other ; six or eight canals diverge from each of the openings 

 into the sponge, forming an ill-defined star within each of the open- 

 ings. 



Diameter 1 to 2 inches ; thickness \ of an inch ; openings 2 to 3 

 lines in diameter. 



Moderately common in all the gi-avel-pits at Little CoxweU. 



This species is easily recognized by the large size of its canal-open- 



