506 J, Hophinson — On New British Grapfolifes. 



of a true solid axis in addition to the axial tube cannot be determined. May not tlie 

 axial tube with its terminal vesicle be merely a modification of the ordinary common 

 tube or periderm ? Such a modification seems more probable than the superaddition 

 of a distinct organ unknown in any other graptolite, or in any recent hydroid zoophyte. 



The hydrothecBB of D. penna differ Avidely from those of D. vesiciilosus,^ being 

 entirely free from each other to their junction with the periderm. They thus, also, 

 differ in this point, as well as in their general form, from those of D. pristis (His.), 

 to which species J5. penna seems to be nearly allied. 



Loc. Llandeilo : — Frenchland Burn, Moffat (and near Moniare ?), Dumfriesshire. 



3. Diplograptus pinguis, sp. nov. — PL XII., Pig. 7. 



Polypary ovate in form, about half an inch in length, and fully a 

 quarter of an inch in breadth, exclusive of its lateral spines and of 

 the prolongations of the virgula, which terminates proximally in a 

 well-marked radicle and is prolonged distally. Hydrothecae about 

 10 to the inch, with a slender spine at their apex, and with a con- 

 cave aperture extending partly across the polypary at right angles 

 to the axis. 



Commencing with a very slender radicular process, flanked by 

 two equally slender spines, indicating the apices of the first- 

 formed thecEe, the polypary rapidly widens, attaining its full width 

 at about a fifth of an inch from its origin, and then gradually 

 becomes narrower to its distal end, from which the virgula is pro- 

 longed as a slender process for at least half an inch. The hydrothecae, 

 owing to the imperfect state of preservation in which this species is 

 found, are scarcely perceptible, being usually indicated only by 

 their spines, which are slender, vary in length from l-20th to nearly 

 1-lOth of an inch, and form a continuous line with the margin of 

 the aperture. 



I have seen very few specimens of this species, and have only one sufficiently distinct 

 to show the above characters, and this, being a mere pyritous stain on the surface of 

 the shale, has lost the distinct brilliant appearance it had when first exposed, as a 

 fossil, to the light. 



D. armatus (Nich.) is the only species to which B. pinguis bears any resemblance, 

 but this species is very much narrower and has much longer spines, which are 

 described as " broad, tapering, and slightly deflexed," and are thus totally distinct 

 from the minute, slender, spinous processes of B. pinguis. 



Loc. Llandeilo : — Sowen Dod, "Wanlockhead, Lanarkshire. 



4. Diplograptus fimh-iatiis, sp. nov. — PI. XII., Fig. 8. 

 Polypary about half an inch in length and l-16th of an inch in 



breadth throughout, with a minute radicle and lateral spines and a 

 distally prolonged virgula. Hydrothecse about 40 to the inch, 

 overlapping one another for fully half their length, inclined to the 

 axis at an angle of from 10 to 20 degrees, and with mucronate apices 

 and slender spines. Apertures appearing as minute circular or 

 slightly elongated scalariform impressions. 



At the proximal end the polypary is obtusely rounded and fringed 

 with slender spines, the central one representing the radicle. The 

 margins of the polypary are parallel throughout, and are also 

 fringed with these spines, which do not appear to proceed, as usual, 

 from the apertures of the hydrothecse, but from a point which pro- 



^ This species, whether with or without its terminal vesicle, may be easily dis- 

 tinguished from B. 2mstis, to which it has been erroneously referred. In the Mofl'at 

 shales it characterizes a distinct zone, and is not associated with B. pristis. 



