262 HOPLITES. 



spiral of the chambered portion of the tube, to which but one 

 very short evolute hook is attached, by their aptychus, which by 

 its form, its want of strong longitudinal sculpture, and the sur- 

 face covered with granules, is allied to the aptychi of Peri- 

 sphinctes, and by the appearance of auxiliary lobes which are 

 wanting in all other evolute forms. The form of the aptychus 

 decidedly indicates that they are serially to be connected with 

 the Perisphinctes-stem, and the form of the inner w r horls of the 

 geologically old species, which agree entirely in form with Olc. 

 Guastaldinus, indicate strongly their connection with Olcoste- 

 phanus, which is also confirmed by the form of the aperture. 



Thirty-four species. 

 SCAPHITES ^EQUALTS, Sowb. T. 100, fig. 527. 



Genus HOPLITES, Neurn. 



Derived from the group of forms represented by Perisphinctes 

 involutus, with moderately narrow umbilicus and high whorls ; 

 thickness very variable. Margin of aperture and length of 

 body-chamber unknown. Sculpture consisting of divided and 

 curved ribs, which originate near the umbilicus or in the middle 

 of the flanks in small, thickened, primary ribs or a tubercle 

 ribs interrupted on the external side, often separated by a deep 

 furrow, or at least feebler at this point ; ribs enlarged at both 

 extremities, weaker at the middle of the flanks. Lobular line 

 complicated, with branches and numerous auxiliaries ; lobular 

 bodies not very plump ; saddles as wide or (mostly) wider than 

 the lobes. First lateral always longer than the siphonal lobe ; 

 second lateral strikingly short ; auxiliary horizontal or very 

 slighth T dependent. 



Besides the typical representatives of the genus we will here 

 place a small lateral!}' divergent group, which is peculiarly char- 

 acterized by a very narrow umbilicus, very broad, flat ribs, 

 separated by very narrow furrows ; it is this, the group embra- 

 cing Hopl. Dumasianus, Orb., provincialis, Orb., compressisi- 

 mus, Orb., galeatus, Buch, Favrei, Oost., didayanus, Orb., which, 

 in spite of their different appearance, may be included in Hoplites, 

 since the inner whorls indicate a very close relationship with 

 Hopl. Boissieri. 



