158 PARTULA. 



plates, which converge towards the middle, so that there are 

 short plates where the two series meet (pi. 42, fig. 1 jaw of 

 P. lirata, after Semper; fig. 2, central portion of jaw of 

 P. gracilis Pse., after Binney). 



The number of plates on the two sides is unequal, there 

 being in lineata 27.36, in recluziana 34.38, in otaheitana 40.50 

 according to Semper. 



The radula is broad. The teeth form thrice bent transverse 

 rows, as shown in pi. 15, fig. 11, a half row of teeth of 

 P. lirata. The central teeth have the usual quadrate basal 

 plates. In P. amanda, P. rosea, P. varia etc. the length of 

 the basal plate is about twice its width in the middle; the 

 middle cusp is long, reaching to or over the posterior border 

 of the basal plate. Side cusps represented by cutting-points 

 only. The lateral teeth are larger, with the mesooone longer, 

 outer cusp well developed with a strong cutting-point (pi. 

 43, fig. 1, P. varia huaheinensis Garrett; fig. 2, P. rosea 

 Brod.). There are 11 lateral teeth on each side in P. rosea 

 and planilabrum ; 10 in abbreviate, amanda, otaheitana ; 8 or 

 9 in varia, umbilicata, virginea, bilineata, hyalina, lineata, 

 recluziana, canalis-, 5 in gracilis. The marginal teeth are 

 peculiar in form, having a long, curved basal plate and 3 

 cusps, the inner largest, the other two directed outward (pi. 

 15, fig. 8, 13th to 15th teeth of P. rosea) . They are numer- 

 ous, over 120 in P. virginea. 



The Fijian P. lirata differs from the Society Island species 

 examined by Binney and myself by having the central and 

 lateral teeth shorter and wider, the central scarcely longer 

 than wide. There are 7 lateral and over 50 marginal teeth, 

 the latter of typical shape (pi. 15, figs. 11, 12, P. lirata after 

 Heynemann) . 



The radula has been examined in numerous species from 

 the Society, Fiji and Samoan Islands, by Heynemann, Binney, 

 and Semper. I have examined it in P. rosea and varia. 



Genitalia (pi. 43, fig. 5, P. rosea). The penis is well de- 

 veloped. It is more or less distinctly contracted near the 

 distal end, which is swollen. Internally the lower portion is 



