166 PROCEEDINGS OF THE ACADEMY OF 
Morse gives a similar figure. The European Z. virrdulus as 
figured by Lehmann (Z. purus) has a similar dentition; he gives 
23—1—23 teeth, with 3 laterals. 
There are decided side cups as well as cutting points to central 
and lateral teeth. 
Z. indentatus (pl. XVII., fig. 3). The lingual examined has 
38—1—838 teeth, with 3 perfect laterals. Morse counted 53 rows 
of 39—-1—39 teeth, also three perfect laterals. 
4. imatulus (pl. III, fig. 3), has 23—1—23 with 5 laterals. 
Z. minusculus (pl. XXI., fig. 9). Morse’s figure shows four 
perfect laterals. He counted 52 rows of 12—-1—12 teeth. It will 
be noticed that his figure does not show the cutting points of the 
side cups of the central and lateral teeth, which I have found in — 
specimens lately examined from Florida. I found a similar num- 
ber of teeth. 
Z. milium is described by Morse (fig. 6), as having 68 rows, of 
17—1—17 teeth, with only 2 perfect laterals. The next six teeth 
Fig. 6. 
Z. milium. 
are shown to be bifid, not only the one or two transition teeth, 
but the decided marginals. I have also drawn the membrane of 
this species (pl. XVII., fig. 8). I found 18—1—18 teeth, with 3 
laterals. 
The peculiarity of the lingual of this species is the great de- 
velopment of the central tooth. The jaw also is peculiar in having 
vertical channels worn upon its anterior surface, extending down 
to the cutting margin (see fig. 7, copied from Morse). These chan- 
