THE AEENIG AND LLANDEILO EOCKS OF ST. DAVID'S. 665 



striated longitudinally, diverging very slightly from each other, 

 and occasionally giving off very short spine-like branchlets ; 

 hydrothecse about 40 to the inch, producing slightly projecting, 

 rounded denticles, when compressed laterally, and showing 

 minute circular depressions (their apertures) when compressed 

 with the ventral side upwards. 



This very distinct species is chiefly remarkable for the short 

 spinous processes which are here and there given off from the 

 branches, sometimes seeming to be unquestionably true branchlets, 

 sometimes scarcely more prominent than the hydrothecse. The 

 branches are sometimes entire, curving gracefully in varying direc- 

 tions for half an inch or more of their length ; and less frequently 

 they re-branch several times within this distance. A few of the 

 laterally compressed thecse show a subquadrangular impression, 

 about a twentieth of an inch in diameter, the outline of which is 

 alone defined. These impressions may possibly be merely owing to the 

 collapse of the thecas after the removal of the hydranths they have 

 contained. 



Dendrograptus fruticosus, Hall, and I), serpens seem to be its 

 nearest allies. 



We name it after Professor Ramsay, P.R.S., Director of the Geo- 

 logical Survey of Great Britain, who, when mapping this district for 

 the Survey more than thirty years ago, discovered Graptolites for the 

 first time in the locality in which it occurs. 



Log. Lower Llandeilo, Abereiddy Bay (higher zone). 



Dendeogeaptits seepens, Hopk., sp. nov. PI. XXXYII. fig. 3. 



Yery diffuse and straggling in form ; branches robust, transversely 

 striated, bifurcating irregularly at distant intervals ; curvi- 

 linear in direction, frequently being curved to such an extent 

 that entire branches with all their branchlets are completely 

 bent back upon themselves, gradually lessening in width and 

 bifurcating more frequently from their origin (the hydrorhiza) 

 to their extremities. 



This species may be readily distinguished from all others by its 

 serpentine character and straggling form. In its mode of branching, 

 its strong branches, and in their gradual and constantly decreasing 

 width, Dendrograptus fruticosus, Hall, is the only form to which it 

 bears any resemblance ; and this species is undoubtedly its nearest 

 known ally. 



Log. Lower Llandeilo, Abereiddy Bay (lower zone). 



Genus Callogeaptus, Hall. 



Callogeaptus eadiatus, Hopk., sp. nov. PI. XXXVI. figs. 8 a 

 & 86. 



Brit. Assoc. Report, 1872. 



Flabelliform and wide-spreading, about three inches in length and 

 six in breadth; branches slender, apparently conjoined at 



