CHAP. IV. VOLUTILITHES — TYPES OF FORM. 121 



Of the resemblance between the three first, or ful- 

 minata, Scaphella, and magnifica, we shall have to 

 speak hereafter. The group which contains Harpida 

 vexillum and Lapponica, as clearly represent the smooth 

 melons, as hehrcea does the bat volutes (Cymhiola). 

 There is a circumstance, also, regarding H. vejcillum 

 and Lappunica, apparently trivial, but of peculiar in- 

 terest to those who delight in analogical researches : 

 they are the types of the genus Harpida, which, as a 

 whole, we have shown to correspond with the Strombidcs ; 

 and, in proof of this, we remarked that the major part 

 presented the analogous character of the outer lip being 

 carried upwards towards the spire. But this is not the 

 only analogy : at the base of the outer lip, in fine and 

 uninjured specimens of vejcillum and Lapponica, is a 

 slight but very distinct sinus*, rudimentary, as it were, 

 of the distinct lobe in the genuine Stromhi : this is not 

 seen in the next division, represented by H. hehrcea ; 

 but then, again, these latter shells have the top of the 

 outer lip much more advanced on the spire. Costata 

 not only represents, but is actually one of, the Harpida ; 

 while FolutilitkeSy with its few plaits, is equally repre- 

 sented by hidlata or nucleus. 



(109.) The types of form in Volutilithes will now 

 be inquired into. Throughout all the species we have 

 seen, or which have been figured, the typical structure, 

 in regard to the paucity of plaits and the acuteness of 

 the spire, seems almost universal. The first group which 

 unites these sharp-pointed volutes with //. lyriformis, 

 seems to be such shells as V. costariaf, which, by a 

 series of other species furnished with distinct convex 

 ribs, like those of H. lyriformis, lead us, by means of 

 muricina'^., to musicalis and spinosa § (.%. 12, c, in 

 p. 123.) : a third type is represented by the crenidata and 

 hicorona \\ Lam, ; a fourth by his rarispina ; and the 



* This is precisely analogous to the corresponding prototy|>cs, 

 nus and Cyllene. 

 t Ency. Meth. pi. S^o. fig. 9. 

 X Ibid. pi. 383. fig. 1. a, and pi. 384. fig. 3. 

 \ Ibid. pi. 392. figs. 4, 5. || Ibid. pi. 384, figs. 5, i 



