442 S. S. Buckman — The Lobe-line of Ammonites. 



delicate ridges and furrows, which are nearly parallel with the upper 

 and lower margins of the scale, though they tend to turn upwards 

 anteriorly ; the posterior margin is sharply and prominently denti- 

 culated. As we proceed backwards, the scales lose the sharpness of 

 their ornament, and become nearly smooth towards the tail, though 

 the caudal V scales remain prominently striated. The origin of the 

 pectoral fin is present, though not well shown, and here the principal 

 rays seem unarticulated. A few broken up ray-joints mark the 

 position of the dorsal and anal fins, the former occurring 3 inches, the 

 latter 3f inches behind the front of the head. 



Remarks. — The condition of the specimen renders its generic 

 determination a matter of great uncertainty, but I am inclined to 

 place it in Rhadinichthys for the following reasons : —(1), the 

 apparent elongation of the body, on which, however, little weight 

 can be placed; (2), the resemblance of the scales, in shape and 

 ornament, to those of the typical R. ornatissimus, Ag. sp. ; (3), the 

 appearance of the broken rays of the root of the pectoral fin. 

 Specifically I designate it as new, as I am not acquainted with any 

 other form in which teeth of such large proportional size occur with 

 scales of similar conformation and markings. 



Geological Position and Locality. — Knowles Ironstone Shale, Fen- 

 ton, Staffordshire, in the collection of John Ward, Esq., F.G.S. 



{To be continued.) 



III. — On the Lobe-line of Certain Species of Lias Ammonites 

 Described in the Monograph by the late Ur. Wright. 



By S. S. Buckman, F.G.S. 

 HILE recently turning over the plates of this Monograph, my 

 attention was arrested by the lobe-line figured on plate 63, 

 and on looking at the explanation of the plate given on the opposite 

 page, I was much surprised to see that it was stated to be the 

 " Lobe-line of Harpoceras ovatum, magnified." On the same plate, 

 just below (fig. 4) is a side view of the Harp, ovatum with its lobe- 

 line in situ, and I suppose it to be this lobe-line that is magnified. 

 But there must surely be some mistake here. Compare the lobe- 

 line, fig. 7, with that on fig. 4, and notice the much greater width 

 of the siphonal saddle in fig. 4 (than in fig. 7), where, on account of 

 the curvature of the fossil, it would be really smaller. To say 

 nothing of the obliquity of the inner portion of that on fig. 4, where 

 is the first auxiliary lobe (nearly as large as the inferior lateral in 

 fig. 7) to be found in fig. 4? I think it will be apparent that for 

 some reason or other the two lobe-lines are different. But is the 

 lobe-line, fig. 7, the correct lobe-line for such a species as the Harp. 

 ovatum here figured ? I must say No ! Turning for a moment to 

 Wright's description of the lobe-line of Harp, ovatum, page 446, we 

 find it stated, " The suture-line is of the radians type." This is true 

 enough of the suture-line shown on fig. 4, but I think any one who 

 has paid attention to the suture-lines of this class of Ammonites 

 could not possibly say that fig. 7 was a lobe-line of " the radians type." 

 The further description given is accurate as regards fig. 7, but it 



