xiv LIST OF ILLUSTRATIONS 



PACK 



Fig. 23. Transverse section, shell gland, and nervous system of 



Apus cancriformis ..... 103 



,, 24. Metanauplius and later developmental stages of Apus 



cancriformis ...... 109 



,, 25. Ventral views of male and female crayfish . . 116 



,, 26. Appendages of the crayfish . . . .118 



,, 27. Appendages of the crayfish . . . .121 



28. Longitudinal section of crayfish . . . .125 



,, 29. Gastric mill of crayfish ..... 127 



,, 30. Branchial chamber of crayfish . . . .130 



,, 31. Central nervous system of crayfish . . . 135 



,, 32. Eyes of Apus and Pakemonetes . . . .138 



,, 33. Developing ova of Astacus . . . .141 



,, 34. Stages in the development of Astacus . . . 143 



,, 35. Section of advanced embryo of Astacus . . . 147 



,, 36. Head of Periplaneta orientalis . . . . 151 



,, 37. Mouth parts and limb of Periplaneta orientalis . . 153 



,, 38. Dorsal views of female and male Periplaneta orientalis . 155 

 ,, 39. The tracheal, digestive and nervous systems of the Cock- 

 roach . . . . . . .159 



,, 40. The generative organs of the Cockroach . . . 163 



,, 41. Stages in the development of the insect's egg . . 167 



,, 42. Amphioxus lanceolatus, views of the entire animal, the 



velum, and left wall of the pharynx . . .174 



,, 43. Transverse sections of Amphioxus . . .180 



,, 44. Plastic diagram illustrating the anatomy of the pharyn- 



geal region of Amphioxus . . . .183 



,, 45. Nerve cord, circulatory system and branchial bars of 



Amphioxus . . . . . .185 



,, 46. Excretory tubules of Amphioxus . . . .186 



,, 47. Early stages in the development of Amphioxus . . 191 



,, 48. Later stages in the development of Amphioxus . . 193 



,, 49. Transverse sections of embryos of Amphioxus of different 



ages . . . . . . .195 



,, 50. Two views of young larvae of Amphioxus . . 198 



,, 51. Dissections of Scyllium canicula showing the alimentary 



tract and chief venous sinuses . . . 206 



,, 52. The skull, visceral skeleton, vertebral column, pectoral 



and dorsal fins of Scyllium canicula . . . 212 



53- A gill partition and denticles of Scyllium canicula . 221 



,, 54. Dissection of the throat of Scyllium canicula showing 



the afferent branchial arteries .... 223 



