INSTITUTE OF SCIENCE, PHILADELPHIA. 169 



callus on the pillar-edge is irregularly laid on and sometimes shows faint 

 grooves, but I have never seen anything like a true plait on the pillar of an 

 Erato, old or young. There are frequently a few denticles on the body near 

 the posterior end of the aperture, but the line is almost always interrupted 

 toward the middle of the pillar-lip. 



Family STROMBIDtE. 



Genus ROSTELLARIA Lamarck. 



Subgenus Orthaulax Gabb. 



Orlhaulax Gabb, Proc. Acad. Nat. Sci. xxiv. p. 272, 1872. Type O. inornatus Gabb, op. 



cit. pi. 9, figs. 3, 4. Miocene of Santo Domingo. 

 Orthaulax Gabb, Geol. St. Dom., p. 274, 1873 Guppy, Quart. Journ. Geol. Soc, Nov., 



1876, p. 520, pi. xxviii. fig. 8; Tryon, Man. ii. p. 192, 1S83. 

 Hippochrenes (pars) Zittel, Tr. de Pal6ont. ii. p. 258, 1887. 

 Wagneria Heilprin, Trans. Wagner Inst. i. p. 105, 1887. Type W. pugnax Heilprin, op. 



cit. p. 106, pi. 15, figs. 36, 36 a. Miocene of Florida. 



This group was described by Gabb from immature specimens, and no 

 perfect specimen has hitherto been figured, for which reason a good deal of 

 doubt has rested upon it. 



At first, when I examined young specimens of a genuine Orthmilax, I was 

 struck by their resemblance to Leiorhynus Gabb, and at once suspected that 

 the latter was only a young specimen of the former. But on examining the 

 type-species of Leiorhynus I found that this was not the case, since that shell 

 bore evidences of maturity, has a thickened and lirate lip, is not self-envel- 

 oped by the last whorl, and has numerous varices. It is, in short, a form which 

 permanently retains some of the external features of immature Orthaulax 

 while adding to them others whigh are not found in Orthaulax. 



The genus Wagneria of Heilprin is founded on characters which are simply 

 part of the process of mineralization. The type of Wagneria is a siliceous 

 pseudomorph ; the very thick coating of the spire having been only partially 

 replaced by silica, thus leaving a hollow, geodic dome analogous to nothing 

 in the original shell. 



A similar state of affairs is found in many of the fossils of that locality, 

 which present a thickness too great to permit of solid silicification. All the 

 corals, some of the Turritellas, etc., offer examples of this kind. For the 

 rest, the relation of his shell to Orthaulax was not overlooked by Prof 

 Heilprin, though he was misled by the state of his material. The name 

 Wagna'ia in any event was preoccupied, and if the genus had proved valid 

 another name would have had to be substituted. 



Orthaulax is almost intermediate between Rostellaria and Strombus. It 

 differs from HippocJirenes Montfort, to which it was referred by Guppy and 

 Zittel, in the following characters: 



It has not the long, anteriorly produced pillar, nor the widely expanded 

 outer lip ; Hippochrenes has the last whorl, when adult, posteriorly extended 



