Plate XVIII. 



Page 

 Fig. i. Iotrochota varidens n. sp. a styli, b tylota, x 200, c ancora unguifera, half front view, 



d younger and older developmental form, x 1000, e birotulse, x 1400 185 



— 2. Iotrochota oxeata n. sp. a oxea, b tylota, c developmental form, x 200, d ancora ungui- 



fera, nearly front view and side view, e developmental form, x 1000, / birotula, x 1400 1S6 



— 3. Iotrochota abyssi Cart, a oxeum and stylus, b tylotum, x 200, c ancora unguifera, side 



view, x 1000, d birotula, x 1400 188 



— 4. Iotrochota dubia n. sp. a styli, x 200, b upper end of stylus with small, but distinct 



spines, x 700, c tylotum, x 200, d ancora unguifera, about from behind and side 

 view, the former showing the long teeth connected with the shaft, x 1000, c birotula, 

 f birotula from the end, x 1400 189 



— 5. Iotrochota inter media n. sp. a styli, b tylotum, x 200, c ancora unguifera, side view, a 



little from the front, x 1000, d birotula, x 1400 190 



— 6. Iotrochota rotulancora n. sp. a styli, b tylotum, x 200, c ancora unguifera, side view, 



showing a tooth connected with the shaft, d the same, side view a little from behind 

 with all teeth free, e an older developmental form, x 1000, / birotula, g an older deve- 

 lopmental form, x 1400 I 9 I 



— 7. Iotrochota polydcntata n. sp. a styli, b tylotum, x 200, c birotula of the large form, 



x 1000, d birotula of the small form, e optical section of one end, showing the differ- 

 ence from the same spiculum in I. affinis, x 1400 192 



— 8. Iotrochota affinis n. sp. a styli, b tylotum, x 200, c birotulse of the large form, one with 



spined shaft, x 1000, d birotula of the small form, e optical section of one end, 

 showing the difference from the same spiculum in /. polydcntata, x 1400 194 



