EXPLANATION OF THE PLATES. 



(13) 



Fig. 4». View of the broad end of fig. 4. 



Fig. 5. Profile of a oyliudrical embryo. 200 diams. 



Fig. 5a. End view of fig. 5. 



Fig. G. One of the smaller forms of cylindrical embryos. 



200 diameters. 

 Fig. 7. Profile of an embryo, swimming with the clear 



space (d) behind. 200 diameters. 

 Fig. 7* End view of the darker end of fig. 7. 

 Fig. 8. In this embryo the clear space (d) is very large. 



200 diameters. 

 Fig. 8a. The same as fig. 8, contracted, and tlie clear 



space obliterated. 

 Fi". 9. View of the flat side of an oval, concave, disci- 

 form embryo. 200 diameters. 

 Finf. fla. Edge view of fig. 9, showing the double con- 

 cave sides. 

 FiiT. 10. View of the flat side of an ovate, compressed 



embryo. 200 diameters. 

 Fig. lOa. Edge view of fig. 10. 

 Fig. lOb. Broader end of fig. 10. 

 Fig. lO"". Narrower end of fig. 10; the cdia are reversed 



by the embryo. 

 Fig. K-iJ. The month of fig. 10; the cilia are quiet, and 



look like bristles. 500 diameters. 

 Fig. 11. An irregularly ovate, cylindrical embryo, recently 

 attached to a sea-weed, the tentacles (c) just beginning 

 to bud. The vibratile cilia do not move any more, 

 and have begun to decompose. 200 diameters. 

 Fig. 12. A scyphostoma with an incipient horn-like sheath. 

 The cilia are quiet and decomposing. 200 diameters. 

 Fig. 1-2^. View of the actinal end of fig. 12. 

 Fig. 1.3. A scyphostoma with two incipient tentacles; 

 the cilia are still persistent but immovable. 200 diams. 

 Fig. ISa. Actinal end of fig. 13. 



Fig. 14. A scyphostoma with four young tentacles and 



a narrow base, but no horn-like sheath. 200 diams. 



Fig. li'"". The same as fig. 14, with the mouth very 



wide open. 

 Fig. 14b. View of actinal end of fig. 14, showing the 



asymmetrical development of the tentacles (c). 

 Fig. 14<:. The same as fig. 14, with the mouth (c) enor- 

 mously distended, and the tentacles so completely re- 

 tracted as to be undiseernible. 

 Fig. 15. An abnormally developed sc}-phostoma. 100 



diameters. 

 Fig. Ii5. Another form of abnormal development. 100 



diameters. 

 Fig. 10 . Actinal end of fig. 10. 



Fig. 1 7. Actinal end of an individual with three ten- 

 tacles. 100 diameters. 



Fig. 18. Similar to fig. 17, but a little older. 100 diams. 

 Fig. 10. A profile view of a scyphostoma with four ten- 

 tacles, which are only half extended, and the pro- 

 boscis retracted. 200 diameters. 

 Fig. 20. Similar to fig. 19, but the tentacles and base 



more extended. 100 diameters. 

 Fig. 21. Similar to figs. 19 and 20. One of the ten- 

 tacles has seized upon a wandering embryo, and is 

 drawing it toward its mouth. 100 diameters. 

 F\". 22. Actinal end of an individual similar to figs. 19, 



20, and 21. loO iliamcters. 

 Fig. 23. Actinal end, with two double tentacles; the 

 proboscis as in fig. 10, but foreshortened. 100 diams. 

 Fig. 24. Actinal end, with four unequally developed ten- 

 tacles. 100 diameters. 

 Fig. 2.5. Actinal end, with three incipient tentacles (e) 

 of the second group ; the quadrangular mouth is dis- 

 torted. 100 diameters. 

 Fig. 20. Three quarters view of a scyphostoma, with a 

 quinary development of tentacles, and a very large 

 proboscis. 100 diameters. 

 Fi<T. 27. Actinal end, with one tentacle, of the second 



group, imduly developed. 100 diameters. 

 Fig. 28. Actinal end, with three double tentacles. 100 



diameters. 

 Fig. 29. Actinal end, with a three-cornered mouth. 100 



diameters. 

 Fig. 30. Actinal end, showing a captured embryo re- 

 volving in the digestive cavity. 100 diameters. 

 Fig. 31. Profile view of an individual similar to fig. 30, 

 with the tentacles and base fully extended. 100 diams. 

 Fig. 32. Actinal end, the mouth rounded and one ten- 

 tacle forked. 100 diameters. 

 Fig. 33. Profile, with eight tentacles, a slender base, and 



the corners of the lips prominent. 100 diameters. 

 Fig. 34. Three quarters view, with eight well developed 

 tentacles. The outer and inner walls arc made prom- 

 inent. 100 diameters. 

 Fig. 34a. Actinal end of fig. 34, with the tentacles re- 

 tracted to mere papilLf, and the mouth shaped into 

 an eight-sided figure. lOo diameters. 

 Fig. 34b. Actinal end of fig. 34, with tentacles retracted 



and curled inwardly. 



Fig. 35. Profile view, with eight tentacles, one of which 



is drawing the cxcrementitious matter from the open 



proboscis. 



Fig. 30. Actinal end, similar to fig. 34, but the mouth 



contracted to a small oval aperture and the tentacles 



partly retracted and curled inwardly. 100 diameters. 



Fig. 37. Profile of a double-headed scyphostoma, with 



