Genus 2. STRUTHIOLARIA, Lamarck. 



Animal ; disc large, thick, carrying a small horny rudimentary 

 operculum behind, supported in the centre by a stout pedicle 

 which passes into the shell, and serves to support the head; 

 head rather large, prolonged into a cylindrical trunk enclosing 

 the mouth, at the base of which on either side are two long 

 pointed tentacles with eyes at the lower outer side ; no respi- 

 ratory siphon. 



Shell ; oblong-oval, spire exserted, rather obtuse at the apex ; 

 columella curved, truncated at the base, outer lip thickened, 

 slightly sinuatcd towards the lower part. 



A limited genus of mollnsks, inhabiting the shores of New Holland, for 

 a description and figure of whose soft parts we are indebted to the 

 researches of M. M. Quoy and Gaimard. Their chief peculiarity consists 

 in the disk being supported on a stout pedicle which passes into the shell, 

 in the truncated proboscidiform prolongation of the head, indicative of the 

 relation of this mollusk with Aporrliais, and in the absence of any respi- 

 ratory siphon, winch is so conspicuous a feature in the Parjmrifera, and is 

 formed, as observed in treating of that family, by an elongated fold of the 

 mantle, protuding in an erect position through the basal notch of the shell, 

 for the purpose of supplying water to the breathing organs. 



From the circumstance of the outer lip of the shell of Struthiolaria 

 being unusually thickened and rolled back, whilst a corresponding 

 thickness is displayed in the superincumbent deposit of enamel on the 

 opposite side, described as the columellar lip, the genus was referred by 

 Lamarck to the immediate vicinity of the Tritons and Ranella, regarding, 

 tins structure as an analogue of the varices by which those genera are 

 characterized ; Mr. Gray and M. Deshayes, however, observing the marked 

 resemblance which the shell of Stmtkiolarial^Teseuts to that of Aporrlia'is 

 in the sinuated lip and truncature of the columella, removed the genus 

 under consideration, almost simultaneously, to the family Alata, and their 

 anticipations of its true character have been confirmed in a striking manner 

 by the observations of Philippi and M. M. Quoy and Gaimard. 



Species. 



1. crenulata Lam. 3. papulosa (Buc.) Mart. 5. straminea (Murex.) Gm. 



2. microscopia, Gray. 4. scutulata (2?wc.) Mart. 



Figure. 

 Struthiolaiiia straminea. PI 8. Fig. 38. Shell, showing the thickened 

 outer and columellar lips and truncature of the columella. 



