J. Hophmson — On a New Genus of Graptol'ites. 25 



as long as the width of the polypaiy, and very distinct and deeply 

 divided. Eadicle and lateral spines always well developed. 



From their origin to their distal end, seldom exceeding l-40th of an inch in 

 breadth, the gracefully curved branches present an aspect very different from that of 

 any other species. Springing from the median radicle in opposite directions, just 

 beyond the lateral spines, and where the hydrothecae first commence, they_ take a 

 sudden bend which sometimes brings them nearly parallel ; they then spring out 

 again, making a very wide angle with each other, and again curve gracefully inwards, 

 gradually becoming almost straight. The slight enlargement in the_ axil is not so 

 marked as in any way to represent a spine. It is sometimes almost imperceptible. 

 The radicle is about l-30th of an inch in length, the lateral spines being somewhat 

 shorter, and diverging very slightly from each other. Owing to the slender nature 

 of the branches, and their consequent liability to twist and expose to view different 

 surfaces of the polypary, the hydrothecEe appear to vary very much in form, and are 

 frequently preserved as scalariform impressions. 



Mr. Carruthers figures two distinct species as D. elegans. His " two young speci- 

 mens " (Fig. 86 and 8c) differ from D. elegans (Fig. 8a) in the presence of a well- 

 developed axillary spine, in the general form of the polypary, and in the form of the 

 hydrothecse ; and are referable to B. Morrisii. I have never seen B. elegans with 

 thecse so slightly divided, or rather with the indentations between them extending 

 for such a slight distance across the polypary, as is shown in the enlarged figure {M), 

 so suppose that this also should be referred to B. Morrisii, though it really more 

 nearly resembles B. Mnffatensis. 



Log. Llandeilo : — Dobb's Linn and Hartfell, near Moffat, Dumfriesshire. 



4. Dicellograpsiis Moffatensis, Carr., sp. Didymograpsus Moffat ensis. 

 Carr. (1858), Proc. Eoyal Phys. Soc. Edin., vol. i., p. 469, fig. 3, 

 GraptoUthus divaricatiis, Hall (1859), Pal. New York, vol. iii., 

 Suppl., p. 513, fig. 1-4, Bicranograptus divaricatus, Hall (1865), 

 Grapt. Quebec Group, p. 57. Didymograpsus divaricatus, Nich. 

 (1870), Ann. and Mag. Nat. Hist, series iv., vol. v., p. 351, pi. vii., 

 fig. 4.— PL I., Fig. 4. 



Branches of polypaiy slightly curved, diverging from each other 

 at a considerable angle, and frequently connected at their origin by 

 a corneous membrane. Hydrothecge from 20 to 25 to the inch, as 

 long as the width of the polypary, and free for about half its width. 

 Eadicle and lateral spines long and slender. 



The branches, about l-40th of an inch broad at their origin, gradually widen, 

 attaining a width, towards their distal end, of l-2oth of an inch. Diverging rather 

 acutely at their origin, they slightly expand for a short distance, continuing with a 

 slight inward curve throughout their length ; their angle of divergence being from 

 60 to 90 degrees or more. They are frequently united for about l-20th of an inch 

 by a corneous membrane, and are then less divergent than when they are not so 

 united. The radicle, in some specimens, appears to be only a slight mucronate 

 extension of the polypary, and the lateral spines are scarcely perceptible ; but in 

 others it is fully l-20th of an inch long, the lateral spines being about half this 

 length, and diverging slightly from each other. The hydrothecse are not so deeply 

 divided in proportion to the width of the polypary as in any other species. They are 

 very gracefully curved, and have no depression as in B. Forchhammeri and B. 

 Morrisii ; their free portions curving slightly inwards towards the body of the poly- 

 pary. Hall states that "the surface is marked by a row of small nodes placed 

 obliquely to the direction of the axis, and situated just below, and a little on one 

 side of the bottom of the serrature," but in British specimens these have not been 

 detected. 



The entire absence of an axillary spine suffices to distinguish this species from all 

 others but B. elegans, and from this it differs in the form and dimensions of the 

 polypary ; the branches being more robust and not so much curved, and originating 

 at a more acute angle than in B. elegans. 



