The Gasteropoda, by Dr. J. Perner. 371 



Perner prefers retaining the name Platyostoma, Conrad, to adopting 

 Fischer's Piaphorostoma, which he suggested on account of the name 

 Plat y stoma having been previously used, and he considers the difference 

 in spelling sufficient distinction without reference to the derivation of 

 the word. The seven species included in this genus wei'e with one 

 exception (P. ferriyenum, Pern.) described by Barrande, and were 

 generally placed by him in Natica or Naticella. This has the widest 

 range in time of anv of the genera of the Capulidse, occurring in 

 D-d 4, E-e2, andG-gl. 



Five species are referred to Strophostylus, Hall, all but one of which 

 were previously included in Natica or Prcenatica by Barrande. The 

 genus certainly bears a superficial resemblance to Natica, while on the 

 other hand it has features in common with Platyceras. S. yreyarius, 

 Barr., the first species quoted, is shown to be very variable, and to 

 comprise several forms considered distinct species by other authors, 

 but regarded by Dr. Perner merely as well-marked varieties, with 

 numerous intermediate links, of which an ample series of figures 

 is given. These species occur in E-e 1, F-f 1, f 2, and G-g 1. 



The relationship of some of the members of the Naticidse, Forbes, is 

 not altogether clear. Some authors would place Strophostylus and 

 Platyostoma here, but Perner, as already shown, considers these genera 

 more closely allied to the Capulidse. In the Xaticidse he places 

 Naticella, Miinster, the new genera Himantonia, Pern., and Prosiyaretus, 

 Pern., as well as the sinistral Sccevoyyra, Whitfield, with its new 

 sub-genus Versispira, Pern., and the new genera Lceoyyra, Pern., and 

 Antispira, Pern. 



A new sub-genus, Naticellina, Pern., is suggested for a species 

 resembling Naticella in the character of the aperture, but differing in 

 its form and spiral ornamentation, which are more like Yanicoro, 

 Quoy & Gaimard. N. suavis, Barr., from E-e 2 is the genotype. 



Himantonia, Pern., is represented by two species whose imperfect 

 state of preservation does not admit of a diagnosis sufficiently well- 

 defined to associate any foreign form with them, though the characters 

 observable show them to be distinct from the members of any previously 

 described genera. In ornamentation they resemble Prosiyaretus, but 

 their shape is distinct. The genotype is II. amoena, Barr. Both 

 species occur in F-f 2. 



Prosiyaretus, Pern., resembles the Tertiary and recent Siyaretus in 

 the form of the mouth, but differs in being ornamented with undulating 

 and ramified grooves. The only species, P. perornatus, Barr., is the 

 genotype, and it is represented by one imperfect specimen from 

 F-f 1. 



Versispira, Pern., is given as a sub-genus of Sccevoyyra, "Whitf., 

 from which it is distinguished by the section of the whorls being 

 reniform instead of sub-triangular, and the aperture is probably of 

 different shape. There are four species. 



Lceoyyra, Pern., is also sinistral, and possesses rounded, flattened 

 whorls having an elliptical section and ornamentation consisting of 

 strong transverse ribs. There is but one specimen known. 



Antispira, Pern., the other sinistral genus, is proposed for a single 

 badly preserved specimen with the general form of the Naticidse. 



