Nicholson — On Grraptolites. 109 



and independent organism, such as Corynoides seems undoubtedly to 

 have been. 



Diplograpsus tuhulariformis, n. sp. (Plate VII. Figs. 12-15). This 

 hitherto undescribed species seems to constitute a transition-form 

 between Corynoides and the true Graptolites, being, however, itself 

 referable to the latter, and belonging to the genus Diplograpsus. 

 The stipe is flattened, simple, from one-third to half an inch in 

 length, celluliferous on the two sides for a short distance above, and 

 tapering gradually towards the base, so as to form a long, pointed, 

 non-celluliferous portion or radicle, which occupies half or more of 

 the entire length of the stipe. The axis is capillary, usually pro- 

 longed beyond the celluliferous portion of the stipe, and apparently 

 double in its composition, as shown by its occasionally splitting at 

 the summit. Celluliferous portion of the stipe from one-tenth to 

 one-eighth of an inch ia breadth, bearing from three to six cellules 

 on each side, and terminating above abruptly bj;- a straight or curved 

 margin, which is usually fringed with terminal cellules. Cellules 

 pointed, about eighteen in the space of an inch, forming a very acute 

 angle with the axis (about 15 degrees) ; their upper portions more 

 or less free ; the upper margin of the denticle directed at right 

 angles with the axis, or more or less downwards. In some of my 

 specimens the broad and tapering radicle, which characterises the 

 species, is present, but the lateral cellules are reduced in number 

 (Figs. 13-14), or seem even to be altogether absent (Figs. 15), when 

 the stipe terminates in a curved or straight celluliferous margin. 

 The pointed denticles, which are seen in these eases, may possibly 

 not be true cellules, but may be due to breakage of the stipe, and 

 under any circumstances this form would appear to be only a variety. 

 In the extreme cases, as in Fig. 15, there seems to be a close 

 approximation to Corynoides. Loc. — Shales of Duffkinnel Burn, 

 near Wamphray. 



Diplograpsus accuminatus, n. sp. (PL VII. Figs. 16-17.) I have 

 proposed this name for a species of Diplograpsus, which occurs 

 pretty generally in the Dumfriesshire shales, and is certainly dis- 

 tract from any described British species. 



Spec. Char. — Stipe celluliferous on both sides ; usually not more 

 than half an inch in length, seldom reaching one inch ; average 

 breadth one-twentieth of an inch ; tapering gradually towards the 

 base, where it ends in a long and pointed radicle. Axis slender, 

 capillary, often prolonged beyond the celluliferous portion of the 

 stipe, for a quarter to half an inch. Cellules about twenty in the space 

 of an inch, alternating distinctly with one another on the two sides 

 of the stipe, and projecting as prominent teeth, the free extremities 

 of which are generally acute and sub-mucronate, sometimes rounded 

 off and obtuse. The cellules are usually one-third as broad as they 

 are long ; their outer margin is straight, or slightly curved, and their 

 upper margin at right angles with the axis — sometimes directed 

 upwards, rarely downwards. This species, when well-marked, as in 

 Fig. 16, is easily recognized by its pointed radicle, which gradually 

 becomes continuous with the body of the stipe, its small width, the 



