1927 SYSTEMATIC 9 



Dec. 



Harpoceratoides is somewhat near in the curve of its radial liu- . 

 but it differs in rib-contour (longitudinally) and in the undulatory 

 character of its inner area — see above, p. 7. 



Radial line and suture-line of Glyptarpites effectually dispose of 

 any association with Hildoceratoides. 



Glyptarpites glyptus, No. 38394 of the collection in the Museum 

 of Practical Geology, London, is the only example of its kind yet noted 

 among more than 1,000 Upper Lias ammonites from Barrington. There 

 is nothing else like it, though the possibility of quite small uncharac- 

 teristic young examples of this, or of congeneric species, having been 

 overlooked may be allowed. Unfortunately, the figured specimen was 

 found loose, so that its exact bed is not known ; but it shows a rather 

 hard argillaceo-calcareous matrix with a greenish-grey tint : such 

 matrix appears to be the same as that of the figured example of 

 Harpoceratoides strangwaysi (PI. DCCXXXIX). Therefore the specimen 

 of G. glyptus is supposed to have come from bed 6 of Barrington, and 

 is assigned to the strangwaysi hemera. 



In the figure of the side-view the part of the suture-line on the 

 inner margin is obscured by shadow, making the inner part of the line, 

 the first auxiliary lobe, look as if it ran obliquely. But this is not so : 

 the other side of the lobe runs forward and the suture-line is of the usual 

 Harpoceratan style — all lobes vertical to the guide-line. 



Taruarpoceras, S.B., Genotype, T. tardum, PL DCCXLI, No. 

 38382 of the collection in the Museum of Practical Geology, London. 

 One feature of this genus is the somewhat late appearance of falciform 

 ribbing (Harpocerate-style) : hence the name tardus. Early ribs are 

 sigmoidal only, rather suggestive of Pseudolioceras-p&ttem : they are 

 of such low relief, especially in the inner area, that they give to the 

 umbilicus and early whorls a smooth appearance which, so far as the 

 inner area is concerned, is not altogether lost when the Harpoceratan-like 

 ribs begin to be formed. This smooth appearance is in considerable 

 contrast to the aspect of Harpoceras falcula, PI. DCLXXXII. 



There are for illustration several forms of small Harpocerates from 

 various beds of Barrington Upper Lias, as well as from other places. 

 Further discussion of them may advisedly await such illustration. 



Poecilomorphus, S. Buckman, 1889, Mon. Inf. Ool. Amm. (Pal. 

 Soc), p. 115, " Type — Poecilomorphus cycloides, d'Orbigny sp." No true 

 type of the genus has yet been chosen from the genosyntypes ; but the 

 type of the species is indicated by its author. Under the name Ammonites 

 cadomensis, d'Orbigny figured (1846, 1845 ?, Ceph. jur. ; Pal. franc., 

 cxxi, 1-5) three examples, whose name he subsequently altered to 

 Ammonites cycloides (Id., p. 370, 1846). He calls the three examples : — 

 figs. 1, 2, " variete renflee," 3, " variete a faisceaux," 4, 5, " variete 

 a ombilic large " (p. 372). But as he gives (p. 370) the dimensions and 

 proportions of figs. 1, 2 only, that example, being thus singled out, 

 becomes the type of his species automatically. 



In quoting the type of the genus I did not mention Ammonites 

 cycloides as being so, but Poecilomorphus cycloides ; so that the genotype 

 should be taken from one of the series which I had handled and had 

 figured under the designation Poecilomorphus cycloides (Mon. Inf. Ool. 

 Amm., PI. xxii, figs. 1-22). In pages 118, 119, I described and 

 arranged these forms, and stated that those depicted in PL XXII, tigs. 

 13-16, 19, 20, " should probably be considered the type-form," an 

 expression which in those days did not necessarily mean the genotype, 

 but merely the most usual or commonest form of the genus. However, 



