262 Nichohon — On Grai^toUtes. 



not think the Graptolites can be referred to any known order, or 

 even sub-class, of the recent Hydrozoa. In many external characters 

 they certainly appear to approximate closely to the order Sertularid(s ; 

 but they are at once excluded from the entire sub-class of the 

 Hydroida by the fact that the polypidom (in the true Graptolites at 

 any rate) was free, and was not fixed by a " hydro-rhiza," there 

 being other important differences as well. As far as the evidence 

 yet collected goes, I should be disposed to believe that the GraiJ- 

 tolitid(s will have to be placed in a new sub-class, which will occupy 

 a position intermediate between the fixed and the oceanic Hydrozoa. 



I may conclude this paper by a short description of a species of 

 Biplograpsus, seemingly distinct from any known form, which I have 

 named after my friend Professor Harkness, to whose researches we 

 owe most of our knowledge of the Graptolitic rocks of Dumfries- 

 shire. The characters of the species are so peculiar that I feel quite 

 justified in describing it as new, though I possess but a single 

 specimen. 



Biplograpsus Harktiessii, n. sp. (Fig. 6), Spec. Ghar. — Stipe three-tenths of an inch 

 in length, and about a line in breadth, celluliferous on the two sides. Solid axis pro- 

 jecting slightly beyond the end of the stipe, slender and inconspicuous. Cellules 

 about thirty in the space of an inch, alternating slightly with one another ; united 

 internally ; but free externally on both sides for about half their length. In the 

 lower half of the stipe the cellules are more closely set, and are only free below. The 

 cellules form somewhat quadrangular tubes, the free extremities of which are bifid, or 

 bi-labiate. In the lower cellules the inferior prolongation of the cell-mouth is fur- 

 nished with a bi-furcate spine or mucro, one arm of which is directed upwards, the 

 other downwards ; but in the upper cellules the spines are not well-preserved, and 

 sometimes appear to be undivided.^ 



Loo. — Hart Fell, near Moffat. 



Germs of Graptolites. — On the surface of the same slab as the preceding are two 

 or three germs apparently belonging to the same species. Each of these (Plate XL 

 Fig. 7) consists of a delicate mucro, or radicle, surmounted by an oval mass, which is 

 indented at the sides, the primary cellules being furnished with spines at their apices. 

 In the shales of Dobb's Linn I have recently observed certain bodies exactly re- 

 sembling in form the di -prionidian germs, so common in all the Dumfriesshire beds, 

 but of a very much greater size. They consist of a long and slender radicle, about 

 four-tenths of an inch in length, with a central solid axis, and with a semi-circular 

 lobe at the top on one side (Fig. 17). Another lobe soon appears alternating with 

 the first, and on the opposite side of the axis (Fig. 1 8) ; and when more advanced two 

 more lobes are super-added to these. These bodies would seem to be the germs of 

 some di-prionidian Graptolite, perhaps of D. teretiusculus ; but their great size is very 

 remarkable and anomalous, the ordinary germs (Fig. 19) being little more than one- 

 twentieth of an inch in length. 



EXPLANATION OF PLATE XI. 



Fig. 1. Pleurograpsus linearis (Carruthers sp), nat. size. The denticles are made 

 much more distinct than they are in nature, for purposes of illustration, 

 and the radicle is put in — though not shown in this particular specimen. 



Fig. 2. Commencement of P, linearis, showing the long and slender radicle. Enlarged. 



Fig. 3. Ditto, without a radicle. Enlarged. 



i_ I take this opportunity of stating that I now am inclined to believe that one 

 variety, at any rate, of the Biplograpsus tubulariformis, which I lately described from 

 the Moffat shales (Geol Mag., Vol. IV. p. 109, Plate VII. Figs. 12-13), is really 

 identical with D. cometa, Geinitz, and must therefore be abandoned as a distinct 

 species. Geinitz's description, however, and figures have been founded on imperfect 

 specimens, and do not recognise the essential characters of the species. 



