56 



xviii INVEETEBEATA 



no. 



30. Section of embryo of Tahularia mesemiryaiithemum sliovving the foriuatiou 



of the aboral tentacles . . • ■ • ■ ■ 



31. Five views of external features of different stages in the development of the 



embryo of Tuiularia indivisa ...... 



32. Two gonophores of Tuhularia iiidivisa with developing embryos inside . 57 



33. Stages ill the development of the Actinula larva of 2'M6Mtorm imc^iOTSffl . 57 



34. Three longitudinal sections through the developing gonophore of Tuiularia 



mesembryanthevnim . . ■ ■ ■ ■ . . 58 



35. Four transverse sections through the developing gonophore of U'ubularia 



mescnibryanthemum . ....... 59 



36. Longitudinal section through very young gouophoi-e-bud of Tuiularia 



meseinbryanihemum to show the origin of the genital cells . . 59 



37. Four stages in the development of the planula of Clytia . . .60 



38. Three stages in growth of the fixed planula of Olytia . ■ .60 



39. A young colony of Clytia reared from a planula in the aquarium . . 61 



40. Two longitudinal sections through the developing medusa of Podocoryne 



cariiea ......... 62 



41. Four transverse sections through the developing medusa of Podomryne 



cariiea in order to show formation of circular canal and endoderm lamella 63 



42. Two longitudinal sections through the developing gonophore of Clava 



squamata ......... 64 



43. Three stages in the development of a Siphonophore {Oystalia monogastrica) 65 



44. Embryo of a Geryonid {Oarmarina fungiformis) in which endoderm cells 



are being budded off ..... . 



45. Early stages in the development of Aurelia aurita . 



46. The fixation of the free-swimming larva of Aurelia aurita . 



47. Two longitudinal sections through two Hydra-tubae of different ages 



48. Two transverse sections through a Hydra-tuba with four tentacles . 



49. A, a Hydra-tuba with eight tentacles. B, longitudinal section of a part of 



a similar specimen in order to show origin of septal funnels 



50. Oral view of Hydra-tuba with twenty tentacles. (The tentacles are repre- 



sented as cut off) ....... 



51. Two horizontal sections through the upper part of a Hydra-tuba, about as 



old as that represented in Fig. 50, to show the formation of the ostium 

 connecting the stomach pockets ...... 72 



52. Two stages in the strobilization of the Scyphistoma of Aurelia aurita . 73 



53. A strobilized Scyphistoma of ^TO-eKffl asitrite . . . . .74 



54. An Ephyra larva of Aurelia aurita just after liberation from the strobilized 



Scyphistoma . . . . . . . .74 



55. Longitudinal section through the sense organ of a young Ephyra . . 75 



56. Three stages in the development of the Ephyra larva into the adult Aurelia 75 



57. An egg of Urticina crassieornis dividing into sixteen blastomeres . . 77 



58. Four stages in the development of the egg of Urticina crassieornis as seen 



in longitudinal sections ....... 78 



59. Two stages in the development of the larva of friiciMa crassicorais . 79 



60. Two transverse sections through a larva of Urtieiim crassieornis in order 



to show the formation of mesenteries . . . . .80 



61. Transverse section through < a larva of Urticina crassieornis in which the 



tentacles have just been developed . . . . . .81 



62. Longitudinal section through the larva of Agarieia agaricites in order to 



show the ectodermal origin of the mesenterial filament . . .82 



63. Stages in the development of the larva of ^cto'mo; cjMJMa . . .84 



64. The Arachnactis larva of Gereanthus inembranaceus . , , .85 



67 

 68 

 68 

 69 

 70 



71 



71 



