40 PE0CKEDING3 OF THE MALACOI.OGICAL SOCIETY. 



{Lepidopleurus), Risso, 1826, is recorded, and as a syDonym Ch. siculus, 

 Gray, 1831, is included. The wrappers of the parts of the Bull. Soc. 

 Malac. Ital. are preserved and bound in, and it appears that p. 145 

 was the first page of a new part, which did not appear until 1878. 

 That is, that the original introduction of Clathropleura did not include 

 Chitoyi siculus, Gray, as a recognizable constituent. According to the 

 International Rules of Nomenclature, this could not therefore be 

 lawfully designated as type. I here designate Ch. Icevis (Pennant) 

 Tiberi, as type of Clathropleura, and that generic name must fall 

 as a synonym of Calhchiton, Gray. 



There is almost as much difficulty in finding a substitute for 

 Clathropleura, Thiele (not Tiberi), and I would use Rhyssoplax, 

 Thiele. In Das Gebiss der Schnecken, vol. ii, 1893, Thiele carefully 

 described the radulte of species of Chiton, and, magnifying the 

 differences observed, introduced many new genera. Having accepted 

 Clathropleura for Ch. siculus, Gray, and Ch. affinis, Issel, he proposed 

 on the next page (p. 368) Rhyssoplax for two species identified as 

 Chiton j'aneiretisis, Gray, and Ch. segmentata, Reeve. On p. 377 

 he proposed Anthochiton for Ch. tulipa, Quoy & Gairaard. Sixteen 

 years afterwards in the Revision Thiele explained that the species 

 identifications were most)}' wrong, having been made when tlie study 

 of Chitons was in the dark ages before Pilsbry's monograph so clearly 

 illuminated it. On pp. 2-4 he correlates the names used in 1893 with 

 the correct name as determined by means of his own work based on 

 Pilsbry's monograph. It is there stated that Rhyssoplax faneiretisis 

 (Gray), Thiele, 1893, and Eh. seymentata (Reeve), Thiele, 1893, both 

 refer to the same species, which is none other than Chiton ajinis, 

 Issel. Further, it is noted that Anthochiton tulipa (Quoy and 

 Gaimard), Thiele, 1893, is really Chiton tulipa, Quoy & Gaimard. 

 Both these he would class under Clathropleura as synonyms, and 

 as that name is untenable I conclude Rhyssoplax must be used. 

 It may be argued that Rhyssoplax, 1893, is indeterminable, and 

 should date from 1909. I quite agree with Thiele that Rhyssoplax 

 cannot be used for janeirensis. Gray. If Rhyssoplax be post- 

 dated to 1909, the question of the usage of Afithochiton at once 

 occurs. That name must be considered as dating from 1893, 

 but since the radular characters given by Thiele for his genus 

 Rhyssoplax are peculiar, I am regarding Rhyssoplax as dating from 

 1893, and having priority over Anthochiton. It is unfortunate that 

 such a delightful and distinct genus should not be in possession of 

 a name without so many complications. I have noted that Chitoti 

 areus. Reeve, from New Zealand, was at one time synonymized with 

 Ch. siculus. Gray, and as Ch. affinis, Issel, was also so considered, the 

 close relationship of the Austro-Neozelanic species to the genotype 

 is obvious. As noted previously, species referable to the genus 

 Rhyssoplax vary from very heavily sculptured forms to absolutely 

 smooth species. I examined a series of Chiton areus. Reeve, and 

 found that the most juvenile specimens were unsculptured, then the 

 sulcations on the pleural areas appeared before the lateral radial 

 ribbing was formed. The following species shows the same method 



