V0LCTID2E. 



the deposition of limy matter begins as a slender cone or elevated 

 point along the line of the axis of the protoconch, and as the 

 larva grows the posterior part of the mantle secretes a shelly 

 dome. Being thus cut off from the horny protoconch, the 

 latter falls into shreds, and is lost. The nucleus of the larva, 

 still in the ovicapsule, then presents a slightly irregular dome, 

 with a slender point rising from the apical part." The horny 

 portion is never found in the fossil state ; but its former presence, 

 where it existed, may be inferred from the scars and irregular, 

 often granulated, aspect of the shelly portion of the protoconch 

 which remains. In those cases where the shell has been rolled, 

 or (with reference to examples of living Volutes) where it has 

 been treated by acid to "clean" it, as with large numbers of 

 shells in our museums, it is often impossible to detect the 

 Scaphelloid type of protoconch, and thus to assign species to 

 their proper systematic position in the VoLUTiDiE. 



Without going into details, it may be observed that Professor 

 Dall has detected three types of Scaphelloid protoconch. Those 

 in which it is pointed he calls the " CaricelW type; the larger 

 and pointless kind is termed the ^^ Scaphella^^ type; and the 

 dome-shaped form is named the " Cyniba " type. That nomen- 

 clature, as well as the terms employed in reference to the Volutoid 

 series, is here adopted. 



The Scaphella type is represented in the Museum collection by 

 several species, of which 8. polita (Plate IV. Figs. Iba-h) is a 

 good example; and the Caricella type (Plate IV. Figs. 16«-J) is 

 well illustrated by a number of species of Eopsephia (see p. 115). 



This is not the place to discuss the geological age of the beds in 

 which the bulk of the Volutes occur ; in deference to the authority 

 of Professor Tate such beds, as at Muddy Creek, Schnapper Point, 

 Cape Otway, etc., are here termed "Eocene." But the writer 

 cannot help remarking that the development of the larval shells 

 of the family now under discussion, in the majority of instances, 

 in such specimens as occur in the beds at the localities mentioned 

 (excluding the upper beds at Muddy Creek), is much more 

 advanced than one would have expected to find in beds as old 

 as the Eocene — that is, on comparison with what is found in the 

 true Eocene in other parts of the world. 



