Vol. 68.] SUCCESSION IN THE NORTH-WEST OF ENGLAND. 567 



calices : but the pores in the coenenchyma of Microcyatlius are irre- 

 gular, and can scarcely be described as a definite tubular system. 



Our form differs again in general appearance by the polygonal 

 character of the calices, which are closely packed ; whereas the 

 cups of Microcyatlms are some distance apart, and circular in 

 outline : also in the absence of a rugose surface and of blunt 

 spines in the calices, which in Microcyathus seem to represent 

 septa. 



Vaughania cleistopoeoides, sp. nov. 



This is the only species of the genus so far known. 



Horizon and locality. — Near tlie base of the Solenopora 

 Sub-zone. Stone Gill and Artlegarth, Ravenstonedale District ; 

 Shap-Abbey Cliff, Shap District. 



BracMopods. 



Camaeotcechia peoava (Phill.). (PI. LI, figs, la-lc.) 



This species was first figured by Phillips in his ' Geology of 

 Yorkshire ' pt. 2 (1836) pi. xii, fig. 37 & p. 223, and described under 

 the name Terehratula proava as follows : — ' Beak produced ; radia- 

 tions obtuse; mesial fold square.' 



Davidson, 'Brit. Poss. Brach.' Monogr. Pal. Soc. vol. ii (1858-63) 

 p. Ill & pi. XXV, fig. 10, refigures Phillips's specimen, and adds the 

 following description : — 



' OF an elongated oval shape, with nineteen or twenty suiall ribs in each 

 valve, but which become obsolete at the beaks ; the mesial fold is of but small 

 ■elevation above the general convexity of the valve, and is ornamented by five 

 i-ibs ; the sinus is shallow.' 



He doubts, however, whether it is a good species, and suggests that 

 it may be an abnormal shape of Camarojplioria crumena. 

 The type-specimen is preserved in the British Museum, 

 Our species resembles very closely figures of Camarotoechia con- 

 (/regata of Hall, from the Hamilton Group of North America.^ 

 The size of the specimen, the slight mesial fold and sinus, and the 

 character of the ribbing all agree. Owing to silicification, it is 

 difficult to find well-preserved specimens exhibiting the interior ; 

 but one or two collected from the Pavenstonedale District show 

 distinctly an incipient spondylium in the brachial valve. This 

 spondylium and the position and shape of the dental sockets 

 correspond almost exactly with the internal view of G. congregata 

 shown in the figures of Hall & Clarke. 



Horizon. — This species forms a very marked band in the upper 

 portion of the Solenopora Sub-zone, and, when present, occurs in 

 great abundance, making up layers of the rock ; it is of great 

 value as a zonal horizon, especially in the type-districts. 



^ J. Hall & J. M. Clarke, ' Palseontology of New York ' vol. viii, pt. ii : ' An 

 Introduction to the Study of the Brachiopocla' pt. ii (1894) pi. xliii, figs. 1 

 & 2-4 (loth Ann. Rep. State Geol. N.Y. for 1893, vol. ii). 



