318 
Fig. 11. Odontotlieca trispinosa Cought. A pair of hydrotnecae, seen 
from the frontal surface of the branch. The stalk-mark shows 
a translucent inner cavity. X 47. 
— 12—13. The same species. The distal end of a hydrotheca, seen in 
two slightly different positions, but mainly from the adcauline 
surtace and partly from above. In fig. 13 is seen the translucent 
abcauline sinus. The line springing from the adcauline tooth 
indicates the ridge of the angularly bent adcauline membrane. X 66. 
— 14. An optical longitudinal section of a hydrotheca showing the 
inner cavity of the stalk-mark. X 75. 
— 15. The same species. A hydrotheca seen from the abcauline sur¬ 
face. Distally is seen the abcauline opercular membrane. For 
the rest compare with PI. IV, fig. 24. X 47. 
— 16. A gonotheca of Hebella contorta Markt. X 34. 
— 17. The same gonotheca seen from the distal end. X 34. 
— 18. Idia pristis Lmx. A portion of a branch seen from the frontal 
surface. Near to the distal end of each hydrotheca is seen the 
fold of the adcauline opercular membrane (also seen in the 
other figures). X 34. 
— 19. The same species. Dorsal view. Distinet stalk-marks. X 34. 
— 20. The same species. A somewhat oblique longitudinal section r 
which has cut away the distal ends of the one series of hydro- 
thecae. Distinet stalk-marks. X 34. 
— 21. The same species. The distal end of a hydrotheca, seen from 
the adcauline surface. X 66. 
— 22. The same, seen from the abcauline surface. The presence of a 
special abcauline opercular membrane is only faintly indicated. 
The adcauline sinus with its median projection is seen through 
the thin wall. X 66. 
1. Allrnan, G. J.: 
1 a. 
2 . 
3 . 
Literature. 
Report on the Hydroida t collected during the expedi- 
tions of H. M. S. “Porcupine” (Transactions of the Zo- 
ological Society of London, vol. VIII, part. VIII, 1874, 
pag. 469—481, pis. 65—68). 
A monograph of the Gymnoblastic or Tubularian Hy¬ 
drofils (Ray Society, London, 1871). 
Diagnoses of new genera and species of Hydroida. 
(Journal Linnean Society, Zoology, vol. XII, 1876, 
p. 251—284, pis. IX—XXIII). 
Report on the Hydroida collected du ring the explo- 
ration of the Gulf-stream by L. F. de Pourtales, (Memoirs 
of the Museum of Comparative Zoology at Harvard 
College, V, No. 2, Cambridge 1877, pag. 1—66, pis. 
I-XXXIV). 
