Three new Species in the Yorkshire Lias

Abstract

Whilst studying the Yorkshire Lias, collecting and identifying its fauna, several forms have been put aside for further and more careful consideration. Three of them have turned out to be species not previously described: Chonetes Clevelandicus, Figs. 1 and 2, is a brachiopod found attached to Waldheimia resupinata, and occurs in the main seam of ironstone in Ammonites spinatus zone at Eston. 3 examples. Pleuromya navicula, Fig. 3, is found in the Ammonites oxynotus zone, Robin Hood’s Bay. Although several specimens have been secured in a fragmentary condition from the shale Fig. 3 is the only perfect one I have been able to obtain, its preservation is due to its pyritous condition. Isis liasica, Figs. 4 and 5. These figures are from fragments of a sclerobasic coral, and are of interest, because I can find no record of any such coral having been found in the Lias, it is of the tribe Isinae. I have noticed it in the Ammonites capricornis and A. Jamisoni zones at Huntcliff and Rockcliff, and A. oxynotus zone, Robin Hood’s Bay. Fig. 4 was picked out of the shale of the last named zone, whilst Fig. 5 is from a sandstone nodule in the first zone. It is common and gives the appearance of a robust horny based coral branching dichotomously, and is inclined to be arborescent, and must have been three or four feet in height. Sections of it under the one inch objective show a coarse cellular structure at the outer margin, this ...