RADULA OF THE MITRID.^. 407 



framework of tlie tooth rather narrow : laterals with 30-32 cusps, 

 deeply rooted, gradually diminishing to the outside. 

 Troschel's figure of the rhachidiau is quite wrong. 



2. M. cardinalis Gmel. tSamoa. Rhachidian 8-cusped, cusps 

 rather short, the 6 interior about equal, the 2 exterior smaller 

 and withdrawn : base very slightly curved : laterals with 13-15 

 cusps, diminishing to mere serrations outside, inside 6 or 7 deeply 

 rooted. Another specimen from Tori'es Strait agrees in essentials. 



3. M. cuaumerina Li2i,rLi. Samoa. 7i^ArtcA«rfirtH 8-cuspecl, with two 

 curious projecting side-pieces, cusps nearly equal, deeply rooted; 

 framework of tooth nari-ow, base slightly rounded below : laterals 

 .about 15, diminishing outwardly, inside 2 smaller, inclining 

 inwards. 



4. M. dujitalis Chem. Samoa. Bhachidian 10-cusped, cusps 

 rather long, deeply rooted, the 6 interioi- cusps more or less equal, 

 4 exterior smaller and projecting sideways; base straight, frame- 

 work of tooth deeper than in cuciomerina : laterals with 28-30 

 denticles, gradually diminishing to the outward end of the tooth, 

 all deeply rooted ; interior 3 or 4 inclining inwards. 



Ill another specimen (also from Samoa) the forward end of the 

 radula tapers away almost to nothing, so that both rhachidian 

 and laterals are gradually much i-educed in size. 



5. Jf. fulva Swfiins. Fiji, lihadddian 8-cusped, cusps rather 

 long and narrow, deeplj^ rooted, the 4 central the largest, outer 

 2 on each side more stumpy ; framework of tooth rather narrow, 

 base straight: laterals with 20-21 cusps, gradually diminishing 

 rio'ht to the end, interior 3 or 4 inclined inwards. 



6. M. glabra Swains. Tasmania. Rhachidian 8-cusped, mode- 

 rately long, but shorter than in falva, central 6 nearly equal, 

 the 2 outside shorter and withdrawn ; framework narrow, base 

 straight : laterals w4th 30-32 cusps, all deeply rooted, gradually 

 diminishing to the end ; framework rather narrow. 



7. M. rhodia Reeve. Port Jackson. Rhachidian 5-cusped on 

 a peculiarly shaped sqiiarish framework, cusps very deeply rooted, 

 the 3 interior the largest, numbers 2 and 4 set at a slight angle 

 to the central cusp ; base straight, upper margin curved : laterals 

 with 15-16 cusps, very deeply rooted, not very sharp, gradually 

 diminishing almost to the end, extreme end bare, inside 3 or 4 

 cusps inclining inwards ; framework of tooth nearly straight. 



8. M. scutulata Chem. E. Indies. Rhachidian 8-cusped on a 

 broadish -oblong framework, cusps deeply rooted, somewhat broad 

 and blunt, projecting well above the upper margin, the 4 central 

 the longest ; base straight : laterals with 26-28 cusps, gradually 

 diminishing to mere points, which continue nearly to the end, 

 about half deeply rooted, cusps 3, 4, 5 (from inside) the largest. 



9. M. stephanucha Mel v. Karachi. The specimen is badly 

 mounted and can scarcely be seen, but the radula apparently 

 belongs to this group. Rhachidian with 3 fairly long cusps, deeply 

 rooted, these are flanked by 2 or 3 smaller cusps on each side : 

 laterals many-cusped, cusps rapidly diminishing in size. 



