J. Hopliinson — On Neio British GraptoUtes. ' 507 



jeets slightly beyond the general margin of the polypary, and ap- 

 parently forms the extreme distal termination of each hydrotheca. 

 Their apertures do not reach to this point, and in the usual direction 

 in which the graptolite is compressed, appear in the centre or between 

 the centre and the margin of the polypary, as circular or oval depres- 

 sions. The spines are about l-20th of an inch in length, and are usually 

 slightly curved. The form of the hydrothecse cannot be accurately 

 determined, owing to the direction in which the species is compressed. 

 Distally the polypary ends abruptly, never contracting, as it almost 

 invariably does in other species, and the virgula is prolonged for 

 about half an inch or more. 



This species difers from all others of its genus iu the number of spines with which 

 tlie proximal end is furnished ; and in the parallelism of the margins of the polypary 

 from all but J), vesicidosus, to which species it has not the slightest resemblance in 

 other respects. 



Loc. Llandeilo : — Wanloek "Water, Wanlockhead, Lanarkshire. 



5. Diplograptus Hinchsit, sp. nov. — PL XII., Fig. 9. 



Polypary two or three inches or more in length, and an eighth of 

 an inch in breadth at its widest part; the proximal end furnished 

 with a slender radicle and lateral spines, and the margins with very 

 conspicuous spines about an eighth of an inch apart. Hydrothecas 

 about 24 or 25 to the inch, decreasing but slightly in width from 

 their junction with the periderm to their apertures, which usually 

 ajpjDear as transverse oval impressions on the surface of the polypary. 



Near the proximal end, the polypary, exclusive of its lateral spines, 

 is about l-16th of an inch in breadth, gradually increasing to fully 

 l-8th where the most distal hydrothecse are seen. The first, or radicular 

 spines are bent slightly towards the radicle, the remaining lateral 

 spines being directed outwards. These spines, which average l-8th 

 of an inch in length, are at first in the proportion of about ten to 

 the inch, but the distance between them gradually increases, until, 

 near the distal end of the polypary, there are only eight in the space 

 of an inch. They originate from the polypary in a lateral direction, 

 having apparently budded from the periderm at right angles to the 

 hydrothecae, to which they bear no even numerical proportion. In 

 these respects they are similar to the reproductive capsules which 

 have been observed on Diplograptus pristis (His.) ; but they show no 

 decisive evidence of real analogy with them. That they have had 

 some connexion with the reproductive process, seems, however, not 

 improbable. The exact fomi of the hydrotheca, owing to their 

 being shown as "scalariform " impressions, cannot be determined, but 

 they have evidently had a larger aperture than is usual in this genus. 

 Its transversely long and narrow form appears to be partly due to 

 compression, the entire hydrothecae having most probably been 

 originally similar in form to those of D. putillus (Hall). 



For the illustration of this species I liave chosen three specimens which occur on 

 the same piece of shale, and in the position in which they are figured. Of these, one 

 only appears to be entire and full grown, another is certainly a young form, and the 

 third is only a fragment, but each one illustrates some peculiarity in this curious 

 species. In the smallest specimen, of which the distal end only is seen, beyond the 

 last developed hydrothecse there is an extension of what appears to be the periderm, 



