CONTRIBUTIONS TO PALEONTOLOGY. 75 



DITHYROCARIS NEPTUNI ( n. s.). 

 PLATE I. FIG. 9. 



The caudal portion, consisting of a strong condyle with its 

 appendages, is represented on Plate I. The anterior extremity is a 

 little concave in the centre, rounded at the antero-lateral angles, 

 and very prominent in the middle above. The central portion, in 

 its posterior extension, is a little depressed on each side, with an 

 elevation in the middle, and becomes prolonged into a triangular 

 spine ; the upper central angle rounded, the spaces between this 

 and the sharp lateral angles being slightly concave. On each side 

 is a stronger and much longer lateral spine, which is united by an 

 oblique suture which extends from the posterior junction of the 

 central spine to the margin, halfway to the anterior extremity. 



These lateral spines are broad at the anterior extremity, flat- 

 tened on the lower side, and nearly flat above, except towards the 

 inner lateral edge, when it is slighly angulated, the inner margin 

 being very thin. These spines gradually taper to an acute point, 

 the extreme length to the anterior face of the condyle being about 

 five inches and a half. The surface is lamellose-striate ; the strise 

 upon the lateral spines being directed obliquely outwards, and 

 are stronger towards the margins. 



This genus is known in rocks of Carboniferous age in I^urope, and its 

 occurrence in lower beds in this country would only accord with other facts 

 of like significance. Notwithstanding the difference between the specimens 

 illustrated, and those figured by British authors, I conceive there is no 

 dissimilarity of generic importance. 



The fossil occurs in a sandy shale ; and the small slab of nine inches in 

 width by about fifteen inches in length contains the remains of four or five 

 individuals, showing that in the neighborhood of this locality the animal was 

 not rare. The impressions of these bodies in the stone are chiefly what remains 

 of them, and they all lie in the same relative position regarding the upper 

 and lower surface. The deep rounded cavity made by the strong anterior 

 extremity has unfortunately been ^''artificially completed,'''' so that I cannot 

 have so clear an idea of its form. The figure has been made frotti a cast in 

 one of these impressions, and no restoration has been attempted, the engra- 

 ving having been carried as far as portions of the crust could be discovered. 



Pia. 9. Dithyrocafis neptuni : the caudal joint and tail-spines, from a cast of the cavity 

 left in the stone by the decay of the fossil. 



The specimen is now in the State Museum of Natural History. 



